How to cover concrete ceiling with insulation?

[Innovate1]

Have a safe room/tornado shelter under my porch. It's an 8' x 18' room with access from the basement. Ceiling is hollow core slabs with EPDM over that and then a poured porch. Get some slight condensation in cold weather around the top edges. Thinking some insulation would be good to eliminate condensation and keep the extremes of heat and cool out. Looking at foam board - xps type although I suppose I could use something cheaper since strength and crush resistance isn't an issue. Then I would like to cover it - probably some plywood. I could glue up the foam but thinking tapcons for the plywood. I could attach blocking to the concrete and nail the sheeting to that but it seems like it would just make things more difficult with lots of foam cutting to fit between the blocking. Want to run the insulation down the walls a few feet. The ground outside goes within a few inches of the top so only have big temp swings at the top. Planning a board around the bottom edge of the wall foam so all the foam is covered. 2" on the ceiling and 1" on the walls. A couple lights on the ceiling and conduit for wiring. Was thinking I would repeat that over the plywood but I could run the wiring behind the plywood and it would look a lot cleaner. They make some texture coatings for foam which might be an option. Any suggestions on this?

 

[Innovate1]

I could fasten 1 x 4s over foam and nail or screw sheeting to that. Would make it easy to run wiring under the sheeting although I only have a run to 2 lights.

 

[mike93lx]

I used these to insulate a concrete wall and fasten furring strips for drywall. Worked great

Simpson Strong-Tie 1/4 in. x 3 in. Mushroom-Head Crimp Anchor (100 per Pack) CD25300M - The Home Depot

The Crimp Anchor is an easy-to-install expansion Anchor for use in concrete and grout-filled block. The pre-formed curvature along the shaft creates an expansion mechanism that secures the Anchor in place

www.homedepot.com

 

[Captain Spaulding]

Vapor barrier is critical in that situation. The concrete will still get cold so you have to keep room air away from it or you’ll have moisture behind the insulation and eventually a mess.

Since insulation is useful below grade as well, you might as well go to the floor.

 

[Innovate1]

Vapor barrier is critical in that situation. The concrete will still get cold so you have to keep room air away from it or you’ll have moisture behind the insulation and eventually a mess.

Since insulation is useful below grade as well, you might as well go to the floor.

I am planning foam insulation which serves as a vapor barrier. I am thinking of using spray foam for any gaps where it doesn't fit tightly together. Going to the floor is additional expense and it isn't living space that is heated or cooled.

 

[K'ledgeBldr]

You would most likely just be trapping moisture. Concrete is a sponge- the basement itself is probably the producer of the moisture- but who’s to say it wouldn’t be the exterior side- even with the EPDM.

Besides, it’s just a safe place- hang a light or two and be done.

 

[mike93lx]

Curious, what do you have for ventilation and a door on the shelter?

 

[Innovate1]

Curious, what do you have for ventilation and a door on the shelter?

Exterior, inward swing door (outward swing might get blocked by debris). I ran a small line from the HVAC duct and removed the bottom door threshold. Keep the vent mostly closed. I was considering doing something similar in some new construction in a different area and they had all sorts of requirements for insulation and ventilation - so much that I gave up on having a storm shelter.

 

[mike93lx]

Exterior, inward swing door (outward swing might get blocked by debris). I ran a small line from the HVAC duct and removed the bottom door threshold. Keep the vent mostly closed. I was considering doing something similar in some new construction in a different area and they had all sorts of requirements for insulation and ventilation - so much that I gave up on having a storm shelter.

Thanks. I built a tornado shelter above ground at my current house. Door is out swing so it can't blow in. If it got blocked, we would either have to unbolt it and push it out, or wait for help. I installed a bath fan and drilled a large hole to exhaust it. Intake is via the gap on the bottom of the door. I have an outlet and a battery backup unit for an outage

Using your hvac for ventilation seems problematic during a storm. When the power goes out, you have nothing, right ?

 

[RivennHewn]

I think I’d start with something like this

DRYLOK 1 gal. Clear Interior/Exterior Floor and Wall Basement and Masonry Waterproofer 831981 - The Home Depot

Customize the look of your floor area with the selection of this beautiful DRYLOK Floor and Wall Masonry Waterproofer.

www.homedepot.com

Then the rigid, followed by a real vapor barrier like FSK or similar. Tape your seams.

Ventilation is crucial.

 

[Innovate1]

Thanks. I built a tornado shelter above ground at my current house. Door is out swing so it can't blow in. If it got blocked, we would either have to unbolt it and push it out, or wait for help. I installed a bath fan and drilled a large hole to exhaust it. Intake is via the gap on the bottom of the door. I have an outlet and a battery backup unit for an outage

Using your hvac for ventilation seems problematic during a storm. When the power goes out, you have nothing, right ?

FEMA has plans online to give some ideas on construction if anyone is thinking about doing it. I am not too worried about the door being pushed in and it's metal clad so less likely to get punchered. It's in a corner of the basement below ground so my thinking is it's unlikely to get a direct blow from debris. I don't have a link but a university in Texas made a device to shoot a 2 x 4 at things at speeds a tornado might throw it. Went to the concrete home builders national show about 15 years ago and saw videos of testing. Went right through an OSB and drywall sheathed wall. Halfway through a brick veneer wall and bounced off the concrete wall. As for ventilation the room isn't completely air tight and it's 8 x 18. I think it would be a very long time before I ran out of oxygen but it would be interesting if there is a way to estimate that.

 

[JbTech]

FEMA has plans online...

You mean the same FEMA who bought thousands of trailers after Katrina that were never used?
I'd look elsewhere for my advice.

 

[Innovate1]

You mean the same FEMA who bought thousands of trailers after Katrina that were never used?
I'd look elsewhere for my advice.

They did some dumb stuff but that seems like a poor reason to not at least look at their methods of construction and suggestions for storm shelters. Their shelters didn't fail (that I know of). What you are bringing up is poor management.