[Greenbuilding] SIPs vs. fix/improve the roof/ceiling

[Keith Winston]

When you say the roof sags, do you mean the ridge beam, or sections of 
the roof sheathing?

If you can verify it's structural adequacy, it is tempting to suggest 
simply going over it with foam, as Barbara suggested. You'll have to get 
all the details right (edges, flashing, etc) but that's always true. 
That is likely the cheapest way do it, and also probably "greener" than 
tearing off the roof structure and starting again (considerably less 
material). However, depending on how you do it, it might be hard to add 
more than 4 inches or so. Adding collar ties may be one way to 
strengthen the existing roof if they don't already exist. You may be 
able to bolster a few bad rafters by sistering on good wood.

Another interesting option might be the Polycore panels mentioned 
recently: http://www.polycorecanada.com/products/, if you can get them 
(I have no idea). They would function here like a SIP, but with no 
sheathing and with internal metal studs. You might even mount them 
sideways and use the studs as your roof purlins, though I've never 
minded the breathing space created by wood purlins under a metal roof... 
And I'm not sure I'd like metal studs in that location... Alternatively, 
use the studs normally, and attach the purlins to them.

Keith


Justin Close wrote:
> I have this odd little idea (or is it a dream?) about my current home.  
> I live in a 1955 stick built house with no insulation in the walls 
> (2x4).  The ceiling (2x6 rafters) is sort of insulated: once by some 
> grayish blowin material and then an overcoat of pink fiberglass.  It 
> isn't very well sealed at all or terribly continuous.  The roof itself 
> sags in a few spots (visible from the backyard) and has some problems 
> with flashing around the chimney (centrally located in the house - but 
> the exposed outer brick is decaying and needs to be rebuilt, according 
> to one tradesman). 
>
> My little idea is to remove the roof and replace it with structural 
> insulated panels (SIPs).  This would solidify and straighten out the 
> roof and provide needed insulation and sealing.  It would also allow for 
> less concern when installing lights in the existing ceiling (won't have 
> to penetrate the insulation layer).  Is this possible, practical, 
> sensible? 
>
> Let the discussion ensue...
>
> Justin
>
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-- 
Keith Winston
Earth Sun Energy Systems
Hyattsville, MD 20781
301-980-6325
send me mail at 
keith at the company below
www.EarthSunEnergy.com