SIPS vs Blue Board roof

[Clovis]

I am also going to use the built up method for my place. I have been researching for awhile now and have come up with this, I will either purchase or make a 1" ceiling t and g boards. Then wrap the whole place in vapor barrier then apply a small stuctural foam panel 1.75" thick r-12 (they claim 20???). The panel has a thin sheet of steel on both sides and costs about .45 cents/ square foot. Its about 32 by 48 "s in size and I'm not to sure what industry they are used in. The cottage will not be heated in the winter it's only for summer use so i just need to keep out the heat. Then I was going to horizontally strap the roof with 2x and then put up white or light gray steel roofing. It will not be the standing seam type because it needs vertical strapping for the venting of the roof.

I've found that the price of the foam boards and the sip's are just to cost prohibitive for a house that only will be used 4 months of the year.

[loghomer]

Folks,

I am building a strawbale TF and the frame is just about together and I am starting to think roof.  I was going to go with the stressed skin panels, but like all good projects, $ is getting tight and I was thinking of throwing down OSB on the purlins and cover it with heavy felt/rolled roofing and come back later (maybe years)and stack on 3-4 layers of 2" blue board and 2x rafters (I have a GREAT idea how to do this in my head, but feel free to weigh in here)  My logic is the blue board idea is half the $ but twice (at least) the work, but proably not quite so good.


Thanks for your opinion.

I saw a company on ebay selling several types of used foam board insulation.  It might make that phase more cost efficient.  Here's the link: http://search.ebay.com/_W0QQsassZinsulationdepot

[Don P]

Welcome loghomer 

[shinnlinger]

Wow!

Thanks, that is a good deal and I will seriously consider it.

[mudburn]

I thought I'd give an update on how my roof/insulation system has worked. I don't have the insulation blown in yet, but I have the rafter and roof structure completed which provides the 10" space for the dense pack cellulose which will come later. Since ya'll seem to love photos, I've got a bunch.


This is a view of the back of the house after I started constructing the rafter system with the 10" insulation space.


Just a view from the end of the house to illustrate their construction. Bear in mind, there are other ways of doing this, I'm sure, but one of my objectives was to keep it affordable since I am working without any borrowed money. So, I used materials I milled and salvaged.


A closer look at the rafter system.


And another. I used vertical strapping to which the rafter structures were nailed. I also toe nailed them into the frame purlins. Oh yeah, looking at this photo reminds me, don't count on tar paper to keep out all of the water. Once it gets under the paper, though, it does a really good job of holding it in. I have some sanding to do on my ceiling boards to get rid of water marks that I had hoped to avoid.


All of the rafters installed.


I sheeted the roof with OSB. I was going to use some other material, but OSB was much quicker.


After papering the OSB, I installed vertical and horizontal strapping, to provide ventilation space under the roof metal.


This is a closer view of the strapping (cupola also).


The metal being installed. There are two rows of metal with a 6" overlap and all joints caulked with silicone. Buying the metal as I did was half the price of what it otherwise would've been. The color is irrelevant because it'll receive a commercial coating later (provided by a friend).


Metal completed on the front -- lovely color!?


Metal begun on the back, also two rows with an overlap and all seams caulked.


All done!


One more showing the cupola I added with its new wood siding (probably less than 10 cents worth -- a bundle of pallet company culls costs $2.00).

After I get my porch framed and the roof on it in the next few weeks, I'll have the insulation blown in. There will be access for blowing it in through the cupola and under the gable ends of the roof.

Darryl

[shinnlinger]

Daryl,

Great post!  THat is almost exactly what I plan to do IF I go the blown in route (maybe a trailer load of that recylced foam board might end up here yet) BUt I intend to burn up some of the 2x piles I created milling my timbers building my 10" trusses.

WHat is interesting here is I am doing a cupola as well, but mine will be a little bigger.  I put a steeple on my shop in Oregon, and it rocked, but it quickly grew crowded at gatherings, so my new one here is is going to be about 12x12.  Bedroom?  Office?  Dinner parties?  Who knows, bit I fugured I should do it now, because it aint gunna happen later.

Oh on the metal roof.  With the ribbed stuff (which is what I intend to use) do you need to vent/strap  it as much as you did?  I was thinking the ribs allowed for enogh air movement.  Maybe in New Hampshire?

[mudburn]

I added the cupola for ventilation purposes. If the house was bigger, it would've been cool to have it as a usable space. My younguns already are asking for a ladder so they can get into it.

Regarding the metal roofing and ventilation space, I'm not sure that the ribs provide enough. You can check with the manufacturer or distributor about installation on a residence. I found a metal roofing forum with a "Condensation Issues" category at http://www.metalroofing.com/v2/forums/index.cfm?action=mboard.members.ViewTopics&ForumCategoryID=8 which got me to thinking about ventilation and condensation issues. There was some helpful info on there which led to my decision (along with some other advice) to use vertical and horizontal strapping. Just horizontal strapping probably would've worked, but I ripped poplar 1x6s I milled two years ago down to 1x4s which left 1x2s which were perfect for the vertical strapping. I like the extra ventilation space this yields not just for condensation but if the roof ever leaks around a screw head or a seam, it can't go too far.

Keep us updated on your project.

Darryl

[Jim_Rogers]

If you strap a roof with just horizontal strapping then you'll have to leave some voids between the strap. Should the metal roof leak the straps would hold back the water from shedding over the roofing paper.

At one conference we were shown a slide where this happened and the horizontal straps held back the water and it was unknown to the owner until his roof leaked. After it started leaking he searched for the cause and found that it had been leaking through his roofing for a while and that the material under the roofing paper was a sip panel and it had rotted to the point where it was then unstable.

Strapping vertically first is always the best.

Jim Rogers

[shinnlinger]

Thank Jim and Daryl,

I suppose I will strap both ways as it is  too cheap and easy not to and the consequences of not are certainly significant. 

On a quasi related note, I have a buddy who wants me to build bat houses into the eve of my south facing roof.   I havent picked his brain yet to learn how he wants to accomplish this, but a bunch of bats hanging around for mosquito patrol sounds good to me, and there arent any entranaces on the south side so I wont have to look at too much bat poo if that poses a problem.

As far as my house goes, I hope to put the rest of the purlins up next weekend.

[shinnlinger]

Update and question.

HI guys,

Many month ago a buddy and I went in on a truckload of the 4x8 insulation above.  My buddy did all the talking and well there was 2"stuff in Pennsyvania, but it was delayed, but they had some 2-1/4 and 3 inch stuff in Maine...no thanks....we need it to be all the same thanks.....

Well today, completly unanounced a semi rig full of foam shows up.  Fortunately I was home! 

That said, THere is one pallet  of oddball stuff, but over all it is either 2 or 2-1/8 stuff and most sheets seem to be relatively intact and perfectly workable for a 3 layer build up as I planned to do.

My question is this...it looks to be yellow foam urethane, but it was sold as isocyanate.  Is this stuff the same?  Is it okay to leave this stuff out?  I plan on putting mine in the basement untill needed, but some of the sheets seem wet.

Ps, we havent paid yet, but it seems to be a hair over $11 a sheet which works out to about 2 large (about 2500 sq feet) for me to insulate my roof to r-36.  If it works out I suppose it wil be a good deal

Good thing I didn't need the stuff this spring when I ordered it!

[moonhill]

If it's wet and stacked in a basement, I bet it will grow mold.  Maybe separate the wet sheets and let them dry it should not take long on a nice day.   What is the facing like? Foil or fiberglass re-enforced paper, I have even seen some sort of fiberglass gell coat on them.   Tim B.

[Don P]

It sounds like polyisocyanurate. It has the highest R per inch that I know of, they used to tell us R7/in. The blowing agent is a cfc and gives it a bump in R value but it slowly dissapates, it was the one with "Thermal Drift" so they ended up having to give "aged" R numbers. I like moonhill's idea of drying it well first. Its closed cell if it is piso so should be dry in minutes.

edit; just found a site that gives R5.6 aged

[shinnlinger]

Thanks guys!