DIYbanter - Expansion gap in concrete floor

DIYbanter (https://www.diybanter.com/)

- Home Ownership (https://www.diybanter.com/home-ownership/)

- - Expansion gap in concrete floor (https://www.diybanter.com/home-ownership/72563-expansion-gap-concrete-floor.html)

David

October 9th 04 07:56 AM

Expansion gap in concrete floor

I was doing some repair work in the finished basement which involved
removing lower part of drywall. This exposed a perimeter gap of about
1/2 inch all around the floor slab which was filled with strips of
black cork-like material. This material apparently absorbed the
mosture from the ground soil in many places and had to be removed.
What do I do now? Do I fill the expansion gap with polyurethane caulk
or can I put DryLok type hydraulic cement to permanently seal out any
moisture?

Anyway, what is the purpose of this gap? Was it just to prevent
problems during curing or is it still needed now? Will I cause
structural problems if I fill the gap with cement? The house is 20
years old and the floor slab is in perfect condition with no cracks.

Thanks,
David

Al Bundy

October 9th 04 01:55 PM

(David) wrote in message . com...
I was doing some repair work in the finished basement which involved
removing lower part of drywall. This exposed a perimeter gap of about
1/2 inch all around the floor slab which was filled with strips of
black cork-like material. This material apparently absorbed the
mosture from the ground soil in many places and had to be removed.
What do I do now? Do I fill the expansion gap with polyurethane caulk
or can I put DryLok type hydraulic cement to permanently seal out any
moisture?

Anyway, what is the purpose of this gap? Was it just to prevent
problems during curing or is it still needed now? Will I cause
structural problems if I fill the gap with cement? The house is 20
years old and the floor slab is in perfect condition with no cracks.

Thanks,
David

You're fine with the self leveling urethane (not poly). Hope you put
it in when it was dry tough.
The wall, foundation, and floor are three separate pours. They are not
one piece and there is some movement there. Cement cracks, period. I'm
glad your slap looks in perfect condition. That says something good
about the ground preparation. If you look real real closely, you might
see the hairline cracks that do exist. That is normal too.

kris	October 9th 04 04:00 PM

(David) wrote in message . com...
I was doing some repair work in the finished basement which involved
removing lower part of drywall. This exposed a perimeter gap of about
1/2 inch all around the floor slab which was filled with strips of
black cork-like material. This material apparently absorbed the
mosture from the ground soil in many places and had to be removed.
What do I do now? Do I fill the expansion gap with polyurethane caulk
or can I put DryLok type hydraulic cement to permanently seal out any
moisture?

Anyway, what is the purpose of this gap? Was it just to prevent
problems during curing or is it still needed now? Will I cause
structural problems if I fill the gap with cement? The house is 20
years old and the floor slab is in perfect condition with no cracks.

Thanks,
David

David.

The gap you're talking about is there by design, and should not be
filled with any cement product. All foundation walls, and slabs are
subject to exterior pressures that cause movement. Therefore,
isolating components that are subject to movement from other
components will prevent damage or cracking to the foundation. However,
this joint you've discovered should be sealed with a urethane or
silicon caulking to prevent moisture, and other soil gases from
entering the house.

Hope this was helpful.
kl

John Davies

October 9th 04 05:15 PM

On 8 Oct 2004 23:56:56 -0700, (David) wrote:

What do I do now? Do I fill the expansion gap with polyurethane caulk
or can I put DryLok type hydraulic cement to permanently seal out any
moisture?

If the gap is 1/2 inch or wider you can't just squirt in a silicon
concrete sealer. Buy the necessary amount of foam backing strip that
is sold in the same section of the hardware store as the concrete
sealers. Pound the foam strips into the gaps with a hammer and blunt
piece of wood or plastic (to below the surface of the concrete) then
use a silicone or self-leveling crack sealer. The foam will keep the
sealer from disappearing into the bottom of the gap.

John

John Davies TLCA 14732
http://home.comcast.net/~johnedavies/
'96 Lexus LX450
'00 Audi A4 1.8T quattro
Spokane WA USA

All times are GMT +1. The time now is 08:58 AM.