# Before jumping in do your research. Some problems I see.



## sprinklertech (Oct 24, 2010)

As stated previously in my opinion this should be part of the plumbing trade but until they get some very serious kinks worked out I see it going nowhere. I've done a lot of looking into this over the past few days and to say it is a mess is an understatement.

After researching a few days here's the problems I see so far.

Who does the drawing?

Most states require a holder of a NICET Level III or IV in "Automatic Sprinkler Layout" to hold a license or at least prepare drawings. These people are not professional engineers so they don't "stamp" drawings but they are submitted to building & fire departments "under signature".

I know North Carolina recently adopted a residential fire sprinkler license but drawings do have to be prepared/submitted by either a professional engineer or a NICET III or IV. Other states that require NICET III or IV include South Carolina, Georgia, Tennessee, Alabama, Texas, Louisiana, Kentucky... you get where I am going with this. Not all but most.

Either way you go this will not be cheap. I think you will find most PE's won't go near this for liability issues and the NICET people are all working for companies and, in my opinion, they are *NUTS* to take on the liability without errors and omissions insurance.

Concerning the Uponor systems I have read where some make the statement "it's easy, you just read off a chart....." *This is not true.*

Stand alone residential systems (these are not connected to the houses plumbing) are relatively easy to do NFPA #13D has an alternative method for these systems but check this out...... 

From NFPA #13D "Standard for the Installation of Sprinkler Systems in One- and Two-Family Dwellings and Manufactured Homes"



> 8.*4.4* Pipe shall be sized by hydraulic calculations in accordance with the methods described in NFPA 13, Standard for the Installation of Sprinkler Systems, in accordance with 8.4.5,* *or in accordance **with the following general method for straight-run systems *connected to a city water main of at least 4 in. (102 mm) in diameter [See Table 8.4.4(a) through Table 8.4.4(g)]:
> (1) The system flow rate shall be established in accordance with Section 8.1, and it shall be determined that the flow allowed by the water meter is adequate to supply the system demand and that the total demand flow does not exceed the maximum flow allowed by the piping system components.
> (2) The water pressure in the street shall be determined.
> (3) Pipe sizes shall be selected.
> ...


Take a moment and read that real carefully. The "charts" are relatively easy to follow but do you see where systems hooked to the domestic, where dead ends are prohibited, a system with loops and grids is taking you?

The "easy method" outlined in 13D is for straight systems... the systems connected to the plumbing (Uponor) have to be looped or gridded (no dead ends) which kicks out the "easy way" to do calculations.

For loops and grids the Hardy Cross method is used and here's a *beginners tutorial* if you're bored and want to work at something new. To be honest with you it took me a couple years to become comfortable with using it.. I know how but wWith loops it is harder and grids without a computer can get *insane* depending on what you got. Three connections to an operating sprinkler will almost certainly take a computer unless the technician is well versed in calculations and has a LOT OF TIME that you will pay for.

It seems that Uponor spent a lot of time getting ready to sell their product not bothering to set ground work that would keep residential plumbers away from some *very serious liability issues*.

For example make sure your liability insurance provides coverage for fire sprinkler completed operations. Just because you have liability in plumbing operations doesn't mean it extends to sprinklers.

Some insurance companies won't even write a policy unless the sprinkler/plumbing company has a full time NICET III or IV employee on staff.

I should add the NICET has to be in Automatic Sprinkler System Layout and not Inspections. A NICET certified inspector will not fly.

Some here may accuse me of trying to talk plumbers out of the work... that perhaps I want to keep it all for myself but nothing could be further from the truth. I don't want the work, I don't want to do it and it should be plumbers who do one and two family dwellings but everyone is putting the cart before the horse. They didn't lay out the ground work it is as if nobody thought this mess through.

If you want to get into this just make sure you do plenty of research first.


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## hydronicsbob (Oct 6, 2010)

*I would agree*

from a wholesaler perspective, it seems the pex manufacturers are kinda throwing things at the wall to see if something will stick.

I was told we should look at working with a local sprinkler company that will design and sign off on it (I'm in Indiana) and help the res. plumber figure it all out. Things like making sure the designer is given complete and accurate information.

I've had two contractors inquire about it, over the last year, then when they see the information required to get started I get a glazed-look and they don't mention it again.

article #1 here Julius Ballanco, P.E.
article # 2 here Samuel Dannaway, P.E.


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## sprinklertech (Oct 24, 2010)

hydronicsbob said:


> from a wholesaler perspective, it seems the pex manufacturers are kinda throwing things at the wall to see if something will stick.
> 
> I was told we should look at working with a local sprinkler company that will design and sign off on it (I'm in Indiana) and help the res. plumber figure it all out. Things like making sure the designer is given complete and accurate information.
> 
> ...


In article #2 there is this statement



> *In addition to sizing piping by hydraulic calculation NFPA 13D now permits an alternative prescriptive pipe sizing method*. This method starts with a static pressure and uses a series of tables to determine pressure losses to the most remote sprinkler. Regardless of the method chosen the system must meet requirements for both a one sprinkler and two sprinkler flow.


The alternative is much easier but as I pointed out



> 8.*4.4* Pipe shall be sized by hydraulic calculations in accordance with the methods described in NFPA 13, Standard for the Installation of Sprinkler Systems, in accordance with 8.4.5,* *or in accordance **with the following general method for straight-run systems *connected to a city water main of at least 4 in. (102 mm) in diameter [See Table 8.4.4(a) through Table 8.4.4(g)]:


the easier alternative method can not be used except on systems with dead ends. There goes your small diameter pex systems.

But what one could do is lay out a system on a straight, single pipe from where it branches from domestic to the toilet at the end of the system. Most likely you could use 1" Blazemaster CPVC throughout with a little thought. Using this it would be integral to the plumbing AND not have loops and grids which would allow for the easier table method to be used. As far as the installation goes it might even be easier than pex.

And something you professionals probably already know... the more I read about pex the less I am liking it.

If anyone is interested I will make up a small drawing of a typical system to include calculations (using both the tables and standard method of calculation) so you can see for yourselves.

All I need is one to say they are interested and I'll do it.


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## Wafflefryer (Nov 4, 2010)

A tradition tree on a Multipurpose system will be met with much opposition from water authorities do to the long dead ends. A large reason that pex systems have loops is because in ensures circulation. Even if some of the lopps only circulate a cup of water a minute, it is enough to ensure that stagnancy won't take place.

I enjoy your insight SprinklerTech.


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## sprinklertech (Oct 24, 2010)

Wafflefryer said:


> A tradition tree on a Multipurpose system will be met with much opposition from water authorities do to the long dead ends. A large reason that pex systems have loops is because in ensures circulation. Even if some of the lopps only circulate a cup of water a minute, it is enough to ensure that stagnancy won't take place.
> 
> I enjoy your insight SprinklerTech.


Here's a "tree" that would work.

Consider this layout on a single family dwelling.










From the mechanical room where the domestic water enters the home come off with an appropriately sized line (usually you could count on 3/4" or 1") and run it through on a single line terminating at say the cold water feed for the toilet.

This will definitely circulate.

I got to be honest with you all and tell you I am developing a real dislike for pex. The more I read about it the more I dislike it.

I wouldn't use it, there are alternative, easier and cheaper methods just consider the little schematic drawing shown above.

It's a typical small house that is going to take 11 sprinklers the way I have it drawn up. Maybe less if the bathroom is less than 55 sq ft.. Bathrooms 55 sq. ft. and less do not require sprinklers.

With typical city water pressure there is no doubt in my mind the biggest pipe diameter you will have to deal with is 1" and probably 3/4" for the areas downstream the living/dining room area.

Not having loops and grids make the hydraulic calculations very easy. Easy enough to where anyone here, and I mean anyone, can be doing it with relative ease in between 1 and 3 days tops. 

For material I would go with copper or *Blazemaster* CPVC pipe.

FYI Blazemaster is UL Listed and Factory Mutual Approved for use on fire sprinkler systems not just in homes but large systems found in schools, motels, hotels and hospitals. 



> The preferred multipurpose solution.
> 
> When it comes to something as important as choosing a life safety system, you can’t afford to make the wrong decision. That’s why our BlazeMaster® fire sprinkler systems meet the highest quality standards. *Approved for use as a stand-alone or multipurpose design, BlazeMaster fire sprinkler systems offer a superior alternative from a reliability, safety and cost perspective. A BlazeMaster multipurpose system is code-approved to transition to any approved plumbing system, including FlowGuard Gold® CPVC pipe and fittings.*


If you view the approvals Blazemaster is approved for cold water plumbing pipe, it is UL Listed to be buried underground and the working pressure is listed at 175 psi which is nearly double from what I have found on pex.

Every system we do we hydrostatically test to 200 psi minimum and where we have a fire pump (most hotels and motels with a standpipe over 3 stories high) we test to 225 psi.

As you get into the market you are going to want the cover using UL Listed and Factory Mutual approved products provide from a liability standpoint. 

How much money would you have in material on this system? You would be high if you figured $15/sprinkler head (that's high, I pay less than $10 each) and $2/foot for pipe (I pay less than $1.00 for pipe alone) which should cover fittings, hangers etc. Total cost of material might be $700 but I doubt it would be that high... probably closer to $500 to $600.

Time wise how long to install? I figure two guys in one day and that is if they goof off, take a long lunch and plenty of smoke breaks. This is not rocket science here. To be honest with you I would fully expect an experienced workman to do it by himself in one day. I have one experienced workman that I know I could send out on this, by himself, and he'd be finished by noon if he started at 7:00.

The first time you do one you'll make mistakes, you will set the heads wrong for the escutcheons, you'll probably have to re-cut some drops taking two or even three days for your first job but after the third job your crew will have it down.

*So much for home builders alarmist spew about sprinklers adding $20,000 to the cost of the typical three bedroom home.*

To help with understanding consider the following.

Consider NFPA #13D section 8.1.3 having to do with spacing and layout.



> 8.1.3 Sprinkler Coverage.
> 8.1.3.1 Residential Sprinklers That Have Not Been Listed with Specific Coverage Criteria.
> 8.1.3.1.1 Sprinklers shall be spaced so that the maximum area protected by a single sprinkler does not exceed 144 ft2 (13.4 m2).
> 8.1.3.1.2 The maximum distance between sprinklers shall not exceed 12 ft (3.7 m) on or between pipelines.
> ...


Ok, maximum 144 sq. ft., not over 6' off a wall or 12' apart.... this is not good because if you have a room measuring 13'x13' you would need a minimum of four sprinklers to provide property coverage.

Luckily there's *8.1.3.2* that I highlighted. I don't know if they even make the old 12'x12' heads anymore. Everything I use has specific applications.

Let's look at the Viking FREEDOM® RESIDENTIAL PENDENT SPRINKLER VK468 *found here*.

On the third page you can see where these sprinklers are specifically listed for a spacing up to 20'x20' (400 sq. ft. coverage) when supplied with 20 gpm.

The maximum distance off a wall is 10' while the minimum distance between two sprinklers remains at 8'-0".

A few words about hydraulic calculations.

They ain't that hard to do. I promise.

You will hear the terms "most remote" or "hydraulically most remote" but these do not have anything to do with being farthest away from the feed. 

The correct term should be "hydraulically most demanding".

When I drew up the house drawing you'll note the first heads I fed were the two located in the living/dining room area. If dimension A and B were each 9'-6" (19'-0" total room width) while D was 14' and C and E were 6'-0" each I can about guarantee the hydraulically most demanding sprinkler will be the one in the Living Room. With a distance 9'-6" off the wall you will have to use 20'x20' spacing which will require 20 gpm. This said consider the demand for the sprinkler in the bathroom... this head would be the physically most remote but if the bathroom measured but 8'x8' the demand would be 13 gpm regardless of where the sprinkler was placed.

Depending on the coverage area of sprinklers and pipe sizes selected you can move a most remote or demanding sprinkler about anywhere you want it to be. Physical distance away does not mean most remote or hydraulically most demanding.

Before closing on this one anywhere you have two sprinklers in a compartment spaced far apart, say 19'x19', you are going to have trouble with the hydraulic calculations. For example in our living room there are two heads... each requires 20 gpm for a theoretical minimum total of 40 gpm which you just won't get out of most residential systems with 1" feed. What I would do here is add heads in the living room... I would place them so distance between heads didn't exceed 16' and distance off the wall did not exceed 8' so demand would be 13 gpm and not the 20. With two sprinklers flowing there's lots of difference between 26 gpm and 40 gpm.

As far as the end of the system I suppose to keep it circulating why not hook it up to supply the toilet? With a 1" pipe through the house it isn't like it would be to small.


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## sprinklertech (Oct 24, 2010)

Of dwelling units and compartments,

A dwelling unit is defined in 3.3.4 as:



> 3.3.4 Dwelling Unit. One or more rooms, arranged for the use of one or more individuals living together, as in a single housekeeping unit, that normally have cooking, living, sanitary, and sleeping facilities.


So a single family dwelling is one dwelling unit while a duplex has two dwelling units.

A compartment is defined in section 4.1 as



> 4.1 Compartments.
> 4.1.1 A compartment, for the purposes of this standard, shall be a space that is completely enclosed by walls and a ceiling.
> 4.1.2 A compartment enclosure shall be permitted to have openings in walls, provided the openings have a minimum lintel depth of 8 in. (203 mm) from the ceiling.


The key here is the lintel depth of 8". A bedroom would most likely be a compartment whether or not it has a door as long as it has the lintel.

In the previous drawing I have the corridor and living area which are really two compartments as long as the lintel depth (shown as two green lines) is 8" or more in depth.

The reason compartments are important is:



> 8.1.2* Number of Design Sprinklers. The number of design sprinklers under flat, smooth, horizontal ceilings shall include all sprinklers within a compartment, *up to a maximum of two sprinklers*, that requires the greatest hydraulic demand.


Consider a bedroom measuring 14'x14' which could be covered using one *VK468 sprinkler *supplied with 13.0 gpm. This sprinkler can be anywhere in the room as long as it isn't more than 8'-0" off any wall. It doesn't have to be in the middle of the room (probably a light fixture there anyway) it can be as close to 6' off a wall which means it wouldn't be any more than 8' off the far wall. Of course we can have it farther than 8' off a wall but the moment you do this, assume it is 8'-2" off a wall, the demand increases to cover the 18' which is 17.0 gpm.

Let's assume this bedroom has a walk in closet measuring 5'x4' which will require a sprinkler because:



> 8.6.3 Sprinklers shall not be required in clothes closets, linen closets, and pantries that meet *all* of the following conditions:
> (1) The area of the space does not exceed 24 ft2 (2.2 m2).
> (2) The least dimension does not exceed 3 ft (0.9 m).
> (3) The walls and ceilings are surfaced with noncombustible or limited-combustible materials as defined in NFPA 220, Standard on Types of Building Construction.


While not exceeding 24 sq. ft. the least dimension is more than 3' so sprinklers would be required. Actually what the standard is looking for is walk in closets.... those are the ones that are likely to be sprinkled.

A closet measuring 3'-1" x 3'-1" (9.5 sq. ft.) is required to have sprinkler while a closet measuring 3'-0"x8'-0" (24.0 sq. ft.) is not. Again what the standard is looking for is a walk in closet where you can enter with a cigarette hanging from your mouth.

Even if the closet doesn't have a door as long as there is a lintel with a minimum 8" depth it is considered a separate compartment. With the lentil there are two sprinklers but pipe need only be sized to supply one sprinkler head not both. If you don't have the lentil then you have to include both sprinklers in hydraulic calculations which means 26 gpm and not the 13 gpm.

I won't do it (I got to much work to do as it is) but many of you will sub-contract the design work out to a certified designer. We call them "free lancers" and lots to be found using Google "*freelance nicet sprinkler designer*". Most states will accept a NICET III certificate which is one of the qualifications you want to see. Look for someone who is certified *NICET Level III or IV* in "*Automatic Sprinkler System Layout*".

Your design technician will need a *dimensioned* floor plan showing the following:

1. Dimensions. Don't guess, looking at the design criteria for sprinkler heads it makes a whole lot of difference if the room is 15'-11 or 16'-1". If you were to tell me "the room is about 16'x14'" I honestly wouldn't know what to do with it.

2. Lentils. Show lintels for the reason explained above.

3. Lights. If you have ceiling lights we need to know exactly where they are and what they look like. We can't have a sprinkler head and light in the same location. While not in the standards I prefer to keep the sprinkler 1'-0" away from lights, ceiling grills etc.

4. If you have a room with decorative beams, such as sometimes found in family rooms, or sloped ceilings it is important these be detailed. 

5. We need to know the water pressure at the main in the street and the size of the water main. 

6. When doing hydraulic calculations per NFPA #13 (nearly all designers will use this method because it is more accurate and what we are used to) everything is done backwards. We calculate the pipe from the most hydraulically demanding one or two sprinkler heads through the overhead pipe all the way to the street connection. This means we need to know exactly what the length and size of the underground from the street into the building is. We need to know the exact internal diameter... it makes a difference if it is 1.013" or 1.101" in internal diameter. The length means everything.. I would need to know if it is 44'-6" or 98'-0". The more accurate you are in providing the information the better job the freelance can do for you.

We need to know exactly where and how the meter and backflow valves are installed. We need to know size, make and model. I can not begin to impress how important this information is... it can make a huge difference.

For example meters.

We could use the provided in NFPA #13D Table 8.4.4(g)










which indicates with a 3/4" meter we would lose a whopping 8 psi (this would hurt) flowing 23 gpm or we could use the actual loss found on the meter criteria.

Let's say you are using *3/4" Neptune T-10 METER found here*. The actual friction or head loss is really 6 psi which might not sound like much of a difference but it can be.

It is one of those little things were 2.0 psi here added to 3.0 psi there and an extra 1.5 psi there can add up to something meaningful.

Speaking from my perspective it is in nobody's interest to have unanswered questions or inaccurate information.

Take for example 50' of 3/4" copper service into the house for a system requiring 26 gpm.

It makes a difference whether it is type K, L or M.

Type K has an ID of 0.745" and will develop a loss of 0.741 psi per foot for a total of 37.0 psi over the 50' length.
Type L has an ID of 0.785" and will develop a loss of 0.574 psi per foot for a total of 28.9 psi over the 50' length.
Type M has an ID of 0.811" and will develop a loss of 0.490 psi per foot for a total of 24.5 psi over the 100' length.

Wow, a 12.5 psi difference between using Type K or M! That means something and if you don't tell me, if I have to guess, I am going to assume it is Type K just to cover my rear end. Not only is Type M better for me but it costs less for you.

Steel yourself for some weird requests. If the city provided a 3/4" tap with a 3/4" meter I would probably ask you about the possibility to "up size" that portion of water supply from the 3/4" meter into the house to 1". I understand from a plumbers perspective this might not make a whole lot of sense but it does to us sprinkler guys. By up sizing, especially if it is a long length, I will have more pressure to work with inside the house allowing me to space sprinklers farther apart (less sprinklers) and use smaller pipe. It could very well be one of those things where the up size might cost you $200 but save me $300 in material for the inside or, in the case of a 3/4" supply, make it possible.

I hear what many of you are thinking. "But if it is fed by 3/4" how can you get more water by using 1" after the meter?" That isn't the point, I am not looking to get more water (I need 23 or 26 gpm whatever my design is) and what I am looking to do is cut my head loss to the house not getting more water.


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## sprinklertech (Oct 24, 2010)

And finally,

Getting your designer all the information he needs will do two things. It will lower your costs and avoid the potential for fighting disagreements. For example let's say you told the designer the distance from the city water main in the street to the house is 40' and the inspector looks to discover it's 70'. I can tell you with almost complete surety at 70' it is most likely the system will not work. Whose fault is that? Who is going to pay to make it right? (Hint, it will not be the designer who worked from the information provided by you).

Cost wise if you get the design tech everything he needs, the drawings, the water pressure available, type of underground, type of meter and exact distance from the street, meters and backflow devices used, etc, he can probably draw this up in a day. Cost is going to be anywhere from $30/hr to $50/hr for $300 to $500/job but at least this gives you an idea how to approach it.

Many free lancers do this as a side money maker and if you work with one you might even get it for less. Speaking for my brethren if you pay fast and develop a relationship you will get a better deal. If I were doing it, I am not and won't but *if* I was, I would want $400 but if you got me all the information and paid fast I would probably do it for half. Paying fast is handing money over the minute you receive drawings. 

We're no different than you.... who do you take care of first, they guy who makes you wait 75 days or the guy who writes a check on the spot? Who are you more apt to give a "break" to? Yep, we've all been there!

Finding a designer you can work with is going to be the hard thing to do.

Before I leave one thing I need to touch on is elevation especially for you folks who live in hill country.

A column of water weighs 0.443 psi/foot... if the hydrant used to obtain pressure is 30' lower than the house the pressure available at the house will be 0.433*30=13.0 psi LESS. Knowing this is really important! If it is just two or three feet it isn't a big deal but 20', 30' and 50' either way (if the house is lower it's better because more pressure is available) is a big deal.


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## ILPlumber (Jun 17, 2008)

Any opinions on more home damage from an activated sprinkler head rather than using baking soda or a fire extinguisher? Assuming someone is home of course......


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## Redwood (Sep 8, 2008)

Matt said:


> Any opinions on more home damage from an activated sprinkler head rather than using baking soda or a fire extinguisher? Assuming someone is home of course......


Timely application of an extinguishing agent is essential.
If you get it on the fire before a head goes off the yes but sleeping, not home, in a different area of the house?
Lives are saved with sprinklers, plain and simple, property damage is also lower.

In todays home with all the plastics flashover happens fast!


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## sprinklertech (Oct 24, 2010)

Matt said:


> Any opinions on more home damage from an activated sprinkler head rather than using baking soda or a fire extinguisher? Assuming someone is home of course......


I've been doing this for 35 years and on an average I would say I designed 10,000 sprinklers per year for a total of 350,000 sprinkler heads. Close enough, somewhere between quarter and half a million heads.

*I have never had a head "just go off" without reason.*

I have experienced vandalism. 20 years ago I had one "just go off" causing considerable damage. Insurance companies got involved, experts in sprinklers and metallurgy got involved and what they found was convincing evidence someone hit the sprinkler with a foreign object. Turns out it was over a labor day weekend, maintenance was required to work and one of the maintenance people decided to "get back" for having to work so he hit a head with a hammer causing tons of damage. They found his wet clothes in his locker, sprinkler water has a smell and stain you can't miss, and he was fired.

Damage is going to happen from one of two reasons. Poor design and freezing which is poor design.

As far as heads "just going off" the manufacturers just couldn't take the liability. 

*http://www.firesafetytoolbox.org.uk/how-sprinklers-work.html*



> Fire sprinkler systems are the strongest means of protecting your home against fire. Unlike other methods of protection, fire sprinklers work to control the fire long before firefighters arrive. In many cases, the fire is entirely extinguished before the fire brigade arrives. Unlike popular media portrayals, the heads in most fire sprinkler systems don’t go off all at once—and water damage is typically negligible and concentrated in the area where the fire started. In addition, *malfunctions in fire sprinkler systems are extremely rare—approximately one in 500,000 fire sprinkler systems is estimated to malfunction as a result of a manufacturing defect. *When it comes to protecting your home against fire, a sprinkler system is effective, unobtrusive and reliable—and the best option available.


Poor design is failure to keep a minimum distance from heat sources per Table 7.5.5.3 










For example put an ordinary (155 deg) sprinkler within 36" from the front of a wall mounted hot air diffuser is asking for a who lot of trouble. *Learn these tables and do not deviate!*

As far as lights go I maintain a minimum of double... 12" for 0-250 W and 24" from 250-499 W. I never go right to the line... I am always more than required.

I was writing earlier about what your designer needs to know.. he needs to know where these heat sources are so he can avoid them. If someone adds a heat source you and your people must be knowledgeable enough to see the potential for very real problems and do something different!

Another problem we are going to see is freezing especially up north. In Phoenix, the central valley of California and Florida not a problem but in Minnesota if you want to see a heck of a mess go ahead and install that sprinkler pipe in an attic or an outside wall.

This is no different than plumbing cold water pipe... would you run a cold water pipe in Minnesota in an attic? Of course you wouldn't. You wouldn't run a cold water supply pipe down and exterior wall either.

In freeze country I would avoid running pipes in attics like the plague. You do this and you are asking for trouble, some very irate homeowners and an insurance company about to drop your coverage.

In freeze country I would use *sidewall sprinklers like this one* running the pipe in the walls. All piping to sidewall sprinklers could be run in the interior walls 0'-4" to 1'-0" down from the ceiling keeping the pipe and heads in a heated environment. This takes more work, it will cost more money (drilling studs) and it will take more heads (generally speaking the areas of coverage are less) but it can be done. Price wise I can see it adding $500 to $1,500 onto the normal price of running the pipe in the attic.

If you Google fire sprinkler failures I think you will almost invariably find the cause was a sprinkler to close to a heat source or a frozen pipe/sprinkler head. Both of these are the result of poor design or an owner change after the completion of a project. I once had a failure where the owner added a unit heater aimed to blow hot air on a sprinkler located less than 2 feet away. You guessed it, the first time they turned on the unit heater I got a call.

And I am really getting turned off by pex. You can do what you want but I wouldn't touch it. Rodents eat the stuff? Are you kidding me?


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## sprinklertech (Oct 24, 2010)

Redwood said:


> In todays home with all the plastics flashover happens fast!


If you want to read something really scary check out composite wood flooring joists. These are the joists made of 2x4's and composite wood or plywood.

http://www.pacificwoodtech.com/pdf/...ood I-joist Floors, Firefighters & Fire 1.pdf



> When unprotected, any lightweight residential floor/ceiling assembly, either combustible or noncombustible, may fail within just a few minutes of the fire’s ignition. When subjected to a standard ASTM E 119 fire test, for instance, unprotected, fully loaded sawn-lumber floor joists typically fail in eight to twelve minutes. *When fully loaded and subjected to the same fire-test conditions, unprotected wood I-joist floors typically fail in four to eight minutes, depending on flange size and web thickness.* The few minutes of difference in endurance times among the different types of joists is of no practical use to the firefighter for predicting the safety of the floor. It makes sense, therefore, that when there is a serious fire beneath a floor, there is no “safe” amount of time that anyone can remain on that floor. Any floor system


Bear in mind this is unprotected (no drywall) but I have seen plenty of homes with unfinished basements that have exposed I joists.

Four to eight minutes means the floor will collapse before the fire department gets there. Four minutes means you barely have time to get your slippers on and get your family out when you hear the smoke detector.

I know the Palm Beach, Florida fire department will not go into a burning house if it has composite wood floor joists. It's just to dangerous and when composite wood floors fail they don't give any warning or "sag" they just collapse.


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