Dampness in basement- new construction

I had a client call for an inspection of a basement in a brand new home. Client is concerned about continuous dampness in the basement. The builder is ready to close but the client is weary. Here’s the stats:

-Poured concrete walls with sprayed wp membrane
-Walls poured early April
-House built and “in the dry”, basement floor placed first week of May.
-Finish grade June 1
-No interior drain tile, exterior footer drains come into a sump pit and are taking delivering a constant trickle during dry weather.
-Neighboring homes are bone dry

Inspection June 11th- All concrete in basement is damp. Most corners are actually wet with liquid water. RH is 67% @ 68 degrees.

Builder has placed two dehumidifiers which run non-stop and have not had much affect. Builder claims this is latent water from the concrete burning off. My experience is that most new basements are dry and the concrete chalking within a month. Builder did not allow me to photograph.

Any thoughts?:-k

I have no ideas for you but would be concerned just because he wouldn’t let you photograph. Sounds fishy.

I would not buy this house.

Wouldn’t that decision depend on the price and or the builders warranty provisions?

It might be nice to go down into the basement every now and then if
love the musty smell of fungi…:slight_smile: Wait till the raining season comes…!

Have many basements in Texas John?

From what I can gather here, is the possibility of the temperature differential between the ambient air temperature and the temperature of the concrete floor and the concrete wall.
They are sweating.

The only possible way to know if it is sweating or leaking is to tape a piece of tin foil to the wet area of the foundation 12"x12" and the next day, if the surface of the foil is wet, it is sweating caused by moisture in the air. If it is wet under the foil, water is coming in through the concrete.

I have a feeling that the moisture barrier might have been omitted under the floor slab, moisture or heavy sweating would be an indicator.

Not allowed to take pictures does not sound good.

I would advise the client that all necessary steps be taken to correct this problem before attempting to go further with this deal.

Hope this helps a little.

Marcel :slight_smile: :smiley:

Wow. I might have a job on the 19 for the same thing. Only difference is they have 6 dehumidifiers in the basement, 80% of the foundation wall is covered with drywall. Buyer is going to stop the carpeting to be installed. The builder wants to close on the 27th.

Have to be careful when making quick judgement calls on something such as a new, not-fully-cured and dried concrete foundation. Outdoor conditions with ambient high RH air infiltrating or being delivered to the basement through a ventilation system such as an HRV can cause the high moisture levels or add to the ambient moisture from a new foundation’s release of free water.

An example from the Canadian Portland Cement Association book “Design and Control of Concrete Mixtures”:

While the surface of concrete will dry quite rapidly, it takes quite a long time for concrete in the interior to dry.

6" wall drying from both sides:

Ambient conditions: 23 degrees C (73 F); 35% RH

850 days were required for the concrete in the center to drop top to 50%!!!

So the bare walls and slab can be giving up quite a bit of water for months after pouring and cause a false call to be made.

Where’s Johnny Bubbler when you need him?


He can fix basement leaks from the exterior but doesn’t usually talk about psychometrics and inherent concrete properties.

Sprayed on asphalt is damp proofing, not water proofing. Water proofing requires spray emulsion and installation of a rubber membrane.

They damp proof all the time and call it water proofing.

I would have them close the house and run big de-humidifiers for at least a week or two, then re-test.

The builder is blowing smoke.

Don’t let them buy until someone, with licensed authority, and insurance to back them up if they are wrong, puts it in writing.

Hope this helps;

Who would want a new house built with a leaky basement for any price? And are you saying the builder should not be responsible for this? There is no accuse for it.

I’ve been around new construction for around 20 years and never seen a basement with such high humidity (resulting in condensation) that an air conditioner and a dehumidifier could not take care of after the house has been closed up. I just have a hard time believing that this much humidity can be primarily coming from the foundation and/or basement floor.

So true.

The house is in Ohio. Becauseof the colder temperatures in Canada, I would imagine that the curing of concrete in Canada takes longer than Ohio. I have been around new construction most of my life in the Midwest, there is no excuse for this.
The inspector can not tell the buyer to not buy the house but he can tell them when something is not right and refer it to a specialist. And that basement is not right.

There may not be a lot of basements in Texas but John is right on this one.

NO, the builder should fix any real problem and be willing to warranty the house. From the info provided, we don’t know what is happening just yet.

It may be simple or it maybe expensive.

Give me a example of simple?

Until the source of the excess moisture is found it’s hard do know how simple or complex it might be.

All I’m saying is that the buyer should should get the builder to fix it or commit to fixing it if the builders statements don’t hold water so to speak.

If I were the buyer I would have him fix it before closing. The fact that other basements in the adjacent area are “bone dry” tells me something is wrong.

I too believe this to be unusual- hence the post. What I’ve told the client so far is that any amount of standing (liquid) water is too much. The home should be move-in ready when they take possession. In the simplest of terms, I think the owner of a brand new home should be able to place belongings in the basement without fear of water damage. I really don’t care what the builder has to do to make the basement dry- but it has to happen.

Thanks for the posts!