How to insulate a really old room starting from scratch

kdw72697April 7, 2013

Hello Fellow Old House Dwellers,

I opened a giant can of worms (metaphorically speaking) and now I am not sure how to proceed in cleaning up the mess...

My house has a little enclosed 4x8 porch at the back (main) entrance.

The previous owners had vinyl sided the INTERIOR of this little uninsulated room. We lived with it that way for many years.

Now that our family has grown, we hoped to better insulate the space, run some heat, and convert it into a much-needed mudroom. Currently nobody wants to leave their shoes and coats in there because they get cold, and in the winter the frozen mittens and boots stay frozen.

Here is where we are now:

We removed the vinyl siding and underneath it was just some foam board. Only one wall was insulated with fiberglass, and probably not correctly.

In addition to the lack of insulation (which we can fix) I'm not sure there is anything much standing between me and the great outdoors other than the mis-matched, gapped boards!

SO do we tyvek over the whole thing, gaps and all?

Try to find every gap and fill them, then use fiberglass?

Spray foam over all of it?

Give up on the dream of heat and just slap paneling over the gappy boards?

I am in WAY over my head and don't know how to get out!

Here is a link that might be useful: Porch Mess Photos

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Unless you provide heat to the room or leave the door to the house open, it will stay cold in winter. And no matter what you do to the walls, there will be a lot of cold coming from the floor, which looks like concrete directly on the soil.

Short of tearing it down and starting over, remove all the mouldy messy fiberglass, caulk and polyurethane foam the gaps in what you have, fill with tightly fitted polystyrene (expanded or extruded) and cover with plywood or drywall.

    Bookmark   April 7, 2013 at 11:49AM
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With such a small area, I'd go with spray foaming the stud bays--that will fill the gaps and provide better R-value than polystyrene sheets.

Most important, you have to insulate the floor--if it is concrete, add the polystyrene sheets here, then cover with plywood and flooring. If it is a wood floor, try to spray foam from below or use unfaced batts or poly sheets.

    Bookmark   April 7, 2013 at 1:52PM
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We can actually access underneath the porch floor from our basement, so that's good.

The plan was to remove the door between the house and the porch and run a little bit of baseboard in there. It's a little intimidating now that it's all exposed!

    Bookmark   April 7, 2013 at 2:15PM
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Spray foam will give you good sealing against air flow and the best R value in the bays (remember to caulk the sill plates while you have access). Even better is to add an additional inch of rigid foam over the entire surface to give you a thermal break where the studs are. It shouldn't be that expensive for such a small space. If you have access underneath you can just have them spray foam over the entire structure and you'll have happy warm feet.

    Bookmark   April 8, 2013 at 2:46PM
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Professionally sprayed high density foam will do a great job. But the costs for such a small area will not be modest. For the applicators, it's the same setup and travel time as for a large job.

This would a good size for a diy foam spray kit if you're up to it.

    Bookmark   April 10, 2013 at 1:48PM
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Thanks, all!

I now have a spray foam person coming tomorrow for an estimate.

Between that and the carpenter needed to fix the gaps in the wood, this is turning out to be a lot less DIY and a lot more $$$ of a project! But I try to keep reminding myself that this is cheaper than an addition!

    Bookmark   April 10, 2013 at 9:02PM
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If your house is vinyl sided on the outside, usually they went over the original the gaps aren't going through to the outside, just to the next layer which could be rosin paper or the backs of original siding. You don't need to fill the gaps--the foam will do that for your. The carpenter isn't needed for that job, just to do the extra heating.

    Bookmark   April 10, 2013 at 9:39PM
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