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solid foam insulation

BonnieBb's picture

I am building a new house and I would like to cut the 4x8 sheets of solid foam insulation to place between the rafters in the attic, instead of using batts.  Does solid foam insulation have to be covered on both sides?  How fire resistant is it?   The purpose of using solid foam is to cut down on dust in the house, since I live in the dusty and hot desert southwest.  Spray-in insulation is not an option.  Any opinions would be appreciated.  Thanks.  Bonnie

White is poison to a picture!  Use it only in highlights.

Peter Paul Rubens. 1577-1640.

I would add: don't use white in architecture either, except rarely and sparingly.


(post #110158, reply #1 of 40)

soild foam does burn and gives off  really bad gas . I guess that the dessert that you are in gets hot .what is wrong with fiber glass?? you could build a double roof whith an air space in between the two surfaces and have ventilation IE. ridgevent and soffit venting.

(post #110158, reply #3 of 40)

I live in the desert southwest with massive dust storms.  Houses insulated with conventional fiberglass batts have a problem with dust infiltration, even with windows closed.  I was thinking of using solid foam insulation (and lots of caulking) to reduce air (and therefore - dust) infiltration.

White is poison to a picture!  Use it only in highlights.

Peter Paul Rubens. 1577-1640.

I would add: don't use white in architecture either, except rarely and sparingly.


(post #110158, reply #4 of 40)

As I follow-up to your message, I have already built the house and am creating essentially two roof systems; the actual roof itself with soffit vents and solar fans, then insulation at the ceiling level, to keep dust out of the house and expensive air conditioning inside the house.  I have finished the exterior and am now ready to start insulating the interior.

White is poison to a picture!  Use it only in highlights.

Peter Paul Rubens. 1577-1640.

I would add: don't use white in architecture either, except rarely and sparingly.


(post #110158, reply #6 of 40)

Correct me if I am wrong, but I think you provided your own solution. You have built a properly vented roof and now want to insulate the ceiling plane, correct? Reducing air infiltration or exfiltration at the ceiling plane is a function of air tight drywall and sealing all penetrations into the habitable space. Tightly fit solid foam insulation in the joist bays may reduce air movement in either direction but the drywall, vp, and fire stop caulking is much more effective. Dense pack cellulose would be my choice for insulation. It has a higher R value per inch than fiberglass, and reduces air movement to nearly nothing. It is also has a lower flame spread and smoke index than foam.


Dave

(post #110158, reply #9 of 40)

Yes, I have built a properly vented roof and do want to insulate the ceiling plane.  An insulation subcontractor advised against blown-in insulation in the ceiling because he said small pieces of the blown-in insulation would go into the solar-powered attic fan.  He recommended batts instead, but I am not convinced I can stop air infiltration with batts. That is why I was thinking about using solid foam insulation. I am, however, concerned about flammability using solid foam.

White is poison to a picture!  Use it only in highlights.

Peter Paul Rubens. 1577-1640.

I would add: don't use white in architecture either, except rarely and sparingly.


(post #110158, reply #12 of 40)

A layer of 5/8 firecode drywall between you and any flammable products will do the trick.


Gabe

(post #110158, reply #16 of 40)

A layer of drywall over the insulation which I am placing in the attic?

White is poison to a picture!  Use it only in highlights.

Peter Paul Rubens. 1577-1640.

I would add: don't use white in architecture either, except rarely and sparingly.


(post #110158, reply #2 of 40)

Bonnie,


  that is part of a great idea.. but you need to finish it.. Are you familar with SIPS? (structural insulated panels?)  that is what they do, but if you use them you can build your whole house with them.  Thus saving the cost of all of those 2x4's and plywood etc..   Very strong.. super insulation and simple to build with..


         To answer your questions, yes foam is flamable and needs to be covered.  Sheet rock is normal but there is a new fire retardant paint available that also fills that requirement.

(post #110158, reply #5 of 40)

Yes, I am familiar with SIPS.  Such a system is not readily available here.  I have actually built and finished the exterior of the house, and am now ready to insulate the interior.

White is poison to a picture!  Use it only in highlights.

Peter Paul Rubens. 1577-1640.

I would add: don't use white in architecture either, except rarely and sparingly.


(post #110158, reply #7 of 40)

You might want to look at www.buildingscience.com

Look it the information for your region. Also checkout the research papers. There are articles about the advantage of making the attic part of the conditioned space. Specially if you have the HVAC ducts in the attic.

. William the Geezer, the sequel to Billy the Kid - Shoe

(post #110158, reply #8 of 40)

I will check out the website.  There are no hvac ducts in the attic; I have run them through the floor joists.

White is poison to a picture!  Use it only in highlights.

Peter Paul Rubens. 1577-1640.

I would add: don't use white in architecture either, except rarely and sparingly.


(post #110158, reply #10 of 40)

I don't want to make the attic part of the conditioned space because I want to create a barrier between the interior, containing very expensive air-conditioned air, and the desert heat outside the roof.

White is poison to a picture!  Use it only in highlights.

Peter Paul Rubens. 1577-1640.

I would add: don't use white in architecture either, except rarely and sparingly.


(post #110158, reply #11 of 40)

Hiya Miss,
I was curious as to what type of roofing material you are using out there?

 


 


 

 

(post #110158, reply #14 of 40)

I am using flat concrete tiles on the roof of the house I am building.

White is poison to a picture!  Use it only in highlights.

Peter Paul Rubens. 1577-1640.

I would add: don't use white in architecture either, except rarely and sparingly.


(post #110158, reply #13 of 40)

why isn't icynene an option, covered as Gabe suggests for fire protection? It'd be tighter than cutting boards to fit.

(post #110158, reply #15 of 40)

I have lived for three years in Lubbock, Texas so I understand the dust problem but it is not through the ceiling SR or insulation that you will see dust getting in. Your best bet is the fibreglas batts and a good job on the sheetrock. The air and dust infiltration will be at your windows and doors. Cutting foam to fit between bays is a tremendous addition of cost in both labor and materials with a nebulous gain. If you wanted to use it still, I will suggest a better way that is a hybrid.

install the fibreglass batts between bays

Place solid foam insulation over the framing and tape all the joints

Then screw your SR on over the foam.


.

Excellence is its own reward!

 

 

Oh Well,

We did the best we could...

(post #110158, reply #17 of 40)

Out in the wilds of west Texas, where I live, up-to-date construction materials are difficult to find.  Any kind of sprayed-in insulation is a bit of a novelty!

White is poison to a picture!  Use it only in highlights.

Peter Paul Rubens. 1577-1640.

I would add: don't use white in architecture either, except rarely and sparingly.


(post #110158, reply #18 of 40)

Perhaps worth a call...

REYNOLDS FOAM ROOFING & INSULATION

502 E 76TH ST

LUBBOCK, TX 79404

806/745-4850

Given the goals you mentioned, and seeing the benifits of sprayed foam first hand, not much to lose from a phone call...

(post #110158, reply #20 of 40)

Hi Cloud.

I'm the one who mentioned Lubbock. She has only said that she is in the desert southwest so she could be a thousand miles away in Tucson.

Be that as it may, you never understand a dust storm until you've lived through a few. I was offering my info to show her that I understood the problem. I agree that if she can find someone to spray urea or icythene foam, she has many problems solved.

.

Excellence is its own reward!

 

 

Oh Well,

We did the best we could...

(post #110158, reply #21 of 40)

A little trick I use to seek out air leaks in a finished house is to wait for a good windy day and check around all openeing with a lit incense stick.  I turn off the HVAC system and check switchs, plugs, around doors and windows, exhaust fans, dryer vents, and light fixtures, etc. without going to the expense of a blower door test, most of the homes I have tightened up with this method realize anywhere fro  5-15% immediate energy savings.


I guess in a dust storm area you could forego the incense sticks and just look for the dust stains around the leak points :)

(post #110158, reply #22 of 40)

Missed that one! But we can triangulate in to a position on her. "Out in the wilds of west Texas, where I live"... At least we know the state! Plus, if there's no one local, I know a travelling foamer. Does domes and flat roofs. Colorado based, but headed to East Texas soon in his 18-wheel shop. Might be passing right near her.

(post #110158, reply #23 of 40)

Thanks for the insulation tip.  I will call the company.

White is poison to a picture!  Use it only in highlights.

Peter Paul Rubens. 1577-1640.

I would add: don't use white in architecture either, except rarely and sparingly.


(post #110158, reply #19 of 40)

One of your early questions which you seam to have reworded to Gabe is whether foam has to be covered with sheetrock on both sides.

No.

You need the fire barrior on the living side of the foam, both to prevent fire sources from starting a smoulder in the foam, and to hold off the amt of vapours ypou would breathe if a fire did start in the foam. SR on the opposite side would do little.

.

Excellence is its own reward!

 

 

Oh Well,

We did the best we could...

(post #110158, reply #24 of 40)

Thanks for the clarification.  Of course, the living side of the insulation would have drywall anway.

White is poison to a picture!  Use it only in highlights.

Peter Paul Rubens. 1577-1640.

I would add: don't use white in architecture either, except rarely and sparingly.


(post #110158, reply #25 of 40)

I ask this as a layman.

If sand dust infiltration is a concern, should there be a concern for what happens in a vented attic ?

Is it possible, especially if this dust problem is severe enough, that is could blow into the attic during the convective venting process and start accumulating/collecting ?

(post #110158, reply #26 of 40)

With Sprayed in Foam, you don't need any ventilation. As a matter of fact in most cases it's a waste of space.


Gabe

(post #110158, reply #27 of 40)

It's not only possible. It happens with a vengence!

Doing a roof tearoff out there involves dust masks, especiallly with cedar shingles where very void will be packed tight with fine nasty dust. A roof tear off is almost as bad as removing plaster indoors!

Like I said above, you can't understand it until you have lived through a few. It gets every where. Grit in eyes, ears, pillowcases, shoes, teeth, books, etc. I swear, sometimes it seems like it can find it's way into a ziplock baggie and pull the zipper shut behind it. You'll find dust piled up near any crack or openning, even what you thought were tight fitting window sashes.

So the next time this house gets remodeled, there will be a couple of five gallon buckets of dust up in the attic.

.

Excellence is its own reward!

 

 

Oh Well,

We did the best we could...

(post #110158, reply #28 of 40)

Thanks, Piffin -

I can now imagine how bad it is just with my experience with pollen clouds that float around in spring and fall in Virginia.

Which brings up.....Iraq.

I've seen zero mention of eventual problems with silicosis years after the soldiers return.

Troops were heavy breathing sand dust - scarfs, bandanas and whatever else I saw them wearing did not appear to be adaquate.

I don't recall seening any wearing one of those diposable paper masks with exhaust valves.

No different then sawing concrete wearing only a regular paper mask.

(post #110158, reply #29 of 40)

It sure would be nice to either filter the soffit vents or eliminate them completely and provide a different source of fresh air inlet to the attic space. A source that could somehow be controlled to limit dust entry.


 


carpenter in transition

carpenter in transition

(post #110158, reply #30 of 40)

A swirling curve profile along the entire length of the soffit entry so the dusty air hits it and separates the stuff.

Sortof like a cyclone separator.

A spring-loaded trap door could be pulled down to empty it with a long stick with a hook on it.

Someone go get a patent on this idea.