Insulating with foam board... some stuff I learned...

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daveomak

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Nov 12, 2010
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Omak,Washington,U.S.A.
I've been working on this 70 year old house for some time now...   When I replaced the roof, awhile back, I found NO insulation between the tongue and groove ceiling material and the roofing sheathing...  WOW...  no wonder this place is cold...  I removed a skylight during the re-roof..  The framed in hole was covered with OSB and framed in to align with the roof sheathing....   As is noticeable, there is no room for insulation between the roof sheathing and the T&G ceiling...    There were gaps where the T&G butted up to the beams..  Air leakage was very measurable....  Caulked the leaks, put the foam in the skylight re-frame...  Now the house is about 10 degrees warmer....   

Next is to sheet over the T&G pine with T&G insulating foam board @ 5.0 R factor.. that will stop infiltrating air through the T&G Pine ceiling boards, stop moisture migration and provide some insulation....   Then, the fiber sheets will be spray painted with a 50-50 mix of latex paint and fire retardant that is Class A rated...  The sheets are absorbent and may take 2-3 coats....    that should provide adequate fire protection to protect the foam that can put off very toxic fumes....


The ceiling and sky light re-frame....   There is a lot of air infiltration through those joints in the T&G.....


I went on u-tube and found this solution to cutting foam board...    IT WORKS..    click on the left picture and see how

nice the cut is...   I'm amazed how it sliced through those little beads and the nice edge it left....

...This cut is the reason I started this thread...


I used an old putty knife and sharpened it...   belt sander to taper the edge... then a diamond impregnated rubber strop... 

Pretty darn sharp tool now....                                                       ....... original edge ....


.........The tool.......


... T&G Foam board........   Fiber board...                 


 .... The edges of the material......                                             ... the paper / wood fiber sound board that will be sprayed...


It's a bugger working on a ceiling by oneself so this is going to take until late spring to finish...    BUT I did find a great tool on Amazon that should

dramatically make life easier during this project.....  They extend to 12' and are TOTALLY adjustable..  150# recommended load..  I think they are called "Third Hands"...

An amazing tool....   Wish I would have designed and sold them... 


There is NOTHING in this house that is plumb / square / or level.....   it sure adds time to a project.........  lots of time...

BBL when I accomplish more stuff..... 
 
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That's good info Dave!  Be careful though, you now have a very sharp tool that has multiple uses.  Don't toss it in the drawer with the other drywall knives without dulling the edge first.
 
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