Live in New England.
If I re-do my house with vinyl siding, which would go directly over the
present T1-11 wood siding which is in poor shape, does it make sense
to have installed styrofoam (or other) insulation between the T1-11 and
the vinyl ?
a. Would the added insulation R value (no idea what it would be) justify
the added installation cost ?
b. Does it make for a "better" or smoother job ?
c. Anything to be particularly aware of in work like this ?
Most vinyl installers use a styrofoam fan-fold underlayment as a standard
practice over sheathing. It might be usable over T1-11, since it is
The R-values is not great, but you can specify thick stuff that conforms to
the contour of the siding for more R-value.
Here is an idea of what I am talking about:
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I had vinyl siding put over the T1-11 siding. The installers put the
foam insulation between the T1-11 and the vinyl
siding. I don't know if it adds ay more R value. It is an enclosed
carport the floor was raised and insulation in the wall and the vaulted
ceiling. But it is the warmest room in the house in winter and coolest
the rest of the year. That was 13 years ago.
My son installs vinyl siding and always uses the foam under the siding.
But I live in Florida. Except for the last 2 days it never gets too
cold. But does a great job for the AC.
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On 1/24/2005 1:07 PM US(ET), Robert11 took fingers to keys, and typed
It's another level of heat and sound insulation, and offers some
waterproofing. I had 3/8" foam, faced both sides with aluminum foil,
installed under my vinyl siding.
I don't remember what the added cost was, but it was not another stage
of construction. The installer tacked up the foam as he was installing
the siding. I don't know what the R value of my foam was, but every bit
counts up here in the NE.
Since vinyl siding is 'hung' rather than nailed solidly to the wall,
smoother does not enter the picture.
When you get estimates, get them with and without the foam. If the
contractor doesn't mention foam in his contract, ask him about it as if
an afterthought. It may be only a few hundred $ difference.
My foam was folded into a package that was about 2' x 3' and when it was
unfolded it was about 6' or 8' wide by 3' high (three or four folded
panels). It took about 10 seconds or less to tack up the 6' or 8' panel,
except those that had to be cut.
Vapor barriers are better on the inside of the wall, but this
rule seems to be broken very often these days. If I had a choice
I at least would use perforated foam, to let some of the moisture
Given address is infrequently checked. Please reply to group.
Go with the strofoam you can only go so thick as the siding will stick out
beyond the windows frames .
The second go around on my install I had the strofoam installed day and
night difference when the wind blows and rattles the siding.
My next install will be concrete siding.
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