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P.J.
P.J., General Contractor
Category: Home Improvement
Satisfied Customers: 413
Experience:  Various construction experiences, both good and bad, allow me to help others solve their home improvement issues.
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Our bedroom was built over a concrete slab garage floor. We

Resolved Question:

Our bedroom was built over a concrete slab garage floor. We are increasingly having musty smell in the house that seems to originate at that end of the house. SInce we are weekenders, the house sits closed 4-5 days each week.

What can we do to eliminate the problem causing this smell?

Thank you,
Larry
Submitted: 1 year ago.
Category: Home Improvement
Expert:  P.J. replied 1 year ago.

Legacy Built :

Ok. Just to clarify the layout in my head...the bedroom where you seem to notice the smell originating is on the slab and the bedroom you mention having not protection and signs of rotten wood is not on the slab but is on a crawlspace? Is this correct?

Customer:

The entire bedroom was added years ago by previous owners. It appears to have been constructed over what was their garage. The room connects to the house which is over a basement, and to a bathroom which has a crawl space. But both crawl space and basement are quite dry. We did have inspectors here and they thought the house was too tight and did not breathe, thus the ridge vent and all new expanded soffits. But one end of bedroom has nothing overhanging like a gutter, just a small deck raised about a foot above the ground with a sliding door.

Legacy Built :

I understand. The ventilation you've provided in the attic is certainly necessary but it is not likely to solve the dampness that is probably the source of your smell. Is there enough space under the "new" bedroom floor joists above that old garage slab to access that slab and do a moisture test?

Legacy Built :

I suspect that moisture is coming up through that slab because it has no vapor barrier under it.

Legacy Built :

If that is the case then the solution is to install a moisture barrier. Ideally it is placed on the old concrete slab. It can also be placed on the underside of the joists.

Customer:

The whole room has a wood floor, not sure where to look to see how this floor was constructed on the slab without lifting some boards.

Legacy Built :

So there is no access through the foundation outside?

Customer:

That may be the best answer, just not sure where to look, perhaps under sliding door to deck which is where there was quite bit of rotten wood years ago when door installed to replace older door.

Legacy Built :

Yes sir, any area that does not have a moisture barrier between the ground and the interior needs a solution for that. Also, any crawl space area that does not have ventilation needs to have that as well.

Legacy Built :

The type of solutions for this will depend on access I suppose.

Customer:

Is there a way to install a moisture barrier under an existing floor, or a way to ventilate without removing floor?

Legacy Built :

Unfortunately there isn't a good way to install vapor barrier. Ventilation shouldn't be a problem though.

Legacy Built :

There is surely, I hope, some distance above the ground to add some foundation vents.

Customer:

It seems to me that I need to put an awning or more stable structure over this entire end of the house, about 20 feet or so, to keep future water from contacting the foundation. But how would I ventilate an area under a floor?

Customer:

Sorry, your second part arrived after I responded.

Legacy Built :

If you could describe what type of foundation walls you have from the ground level up to floor level I could probably provide some ideas to add ventilation.

Customer:

can I email you from my iphone a photo taken on my iphone

Legacy Built :

You can attach a photo in this chat by using the paperclip icon just above the text entry box

Customer:

The paper clip does not show up on my phone, bear with me two minutes

Legacy Built :

Oh, ok.

Legacy Built :

No problem.

Legacy Built :

Ok. Let me take a closer look.

Customer:

Your not watching the Dodger game?

Legacy Built :

It looks like you have a couple issues that need fixed. It appears that the soil is higher than the old slab. This is essentially causing the old slab to be the low spot and that's where the water is going to sit. Regrading the soil down below the level of the slab and with some slope away will fix most of the issues.

Legacy Built :

Cutting in standard foundation vents to get a little air moving should finish the job.

Legacy Built :

You can cut the brick with a diamond wheel on a grinder and a hammer and star drill or masons chisel.

Customer:

Much appreciated, you have pointed out some things that now seem obvious. So I should lower the dirt level, especially where it comes up against the brick on left side of deck. Does it appear all the earth is too high on both sides of deck, as property slopes down

Legacy Built :

Yes, more so on the left side though.

Legacy Built :

Left side as you face the door.

Customer:

Thanks so much, you have been great. have a nice weekend.

Customer:

Larry

Legacy Built :

You are welcome. Take care.

P.J., General Contractor
Category: Home Improvement
Satisfied Customers: 413
Experience: Various construction experiences, both good and bad, allow me to help others solve their home improvement issues.
P.J. and 3 other Home Improvement Specialists are ready to help you
Expert:  P.J. replied 1 year ago.
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P.J.
P.J.
Home Improvement Expert
413 Satisfied Customers
Various construction experiences, both good and bad, allow me to help others solve their home improvement issues.