Thread: Ventilating a cold weather, unheated basement

Hi all,

I’ve seen some forums on the site about ventilating unheated basements, but none seem to quite address my situation. Here’s my situation:
· We live in New Brunswick, Canada (climate on par with northern Maine)
· We purchased a summer cottage this past June that is really a ~45 year old small house with full basement. There is a porch that was added on that sits on the basement as well, and opens directly to the basement (open concept, no door).
· The basement is very damp. There is a built-in sump, but the lot is relatively wet.
· We planned to get external drain tiles redone, but the contractor did not get to it before the first snowfall, so now it’s on hold until the spring.
· The previous owner installed a 2-speed fan in the stairwell that exhausts air from the basement (he kept 1-2 basement windows open all summer). This kept the basement somewhat dry.
· So, since we are only using the home for the summer, I winterized the whole cottage (drained water lines, shut off all power, except to the sump, closed all windows, etc). We did this in early November.
I came back 3-4 weeks later, and this was the situation:
· I opened the door to the porch, and there was moisture on all the walls.
· The porch ceiling was blackened with mold.
· The exterior door, and the door to the main floor were covered in moisture
· The walls were all moldy
· In the basement (unfinished, no insulation), there was white puffy mold on the floor and wherever it could attach itself (shelves, etc)
· There had been a lot of rain and snow, and water was free flowing into the sump cavity
So, I know I have a mess to clean up in the spring. Hopefully the drain tiles (draining to an exterior ditch) will help reduce moisture. I expect that when the basement temperature drops below freezing, the mold will cease growing.
I figured putting an air exchanger in the basement and running it all winter might resolve the situation. Further research seems to indicate that these don’t work well in cold weather as the heat recovery unit (which I don’t actually need) will freeze up.

Does anyone have a suggested solution to my problem?
If you need more info as well, let me know.

Thanks
Brian

Originally Posted by Brian Doyle

Hi all,

I’ve seen some forums on the site about ventilating unheated basements, but none seem to quite address my situation. Here’s my situation:
· We live in New Brunswick, Canada (climate on par with northern Maine)
· We purchased a summer cottage this past June that is really a ~45 year old small house with full basement. There is a porch that was added on that sits on the basement as well, and opens directly to the basement (open concept, no door).
· The basement is very damp. There is a built-in sump, but the lot is relatively wet.
· We planned to get external drain tiles redone, but the contractor did not get to it before the first snowfall, so now it’s on hold until the spring.
· The previous owner installed a 2-speed fan in the stairwell that exhausts air from the basement (he kept 1-2 basement windows open all summer). This kept the basement somewhat dry.
· So, since we are only using the home for the summer, I winterized the whole cottage (drained water lines, shut off all power, except to the sump, closed all windows, etc). We did this in early November.
I came back 3-4 weeks later, and this was the situation:
· I opened the door to the porch, and there was moisture on all the walls.
· The porch ceiling was blackened with mold.
· The exterior door, and the door to the main floor were covered in moisture
· The walls were all moldy
· In the basement (unfinished, no insulation), there was white puffy mold on the floor and wherever it could attach itself (shelves, etc)
· There had been a lot of rain and snow, and water was free flowing into the sump cavity
So, I know I have a mess to clean up in the spring. Hopefully the drain tiles (draining to an exterior ditch) will help reduce moisture. I expect that when the basement temperature drops below freezing, the mold will cease growing.
I figured putting an air exchanger in the basement and running it all winter might resolve the situation. Further research seems to indicate that these don’t work well in cold weather as the heat recovery unit (which I don’t actually need) will freeze up.

Does anyone have a suggested solution to my problem?
If you need more info as well, let me know.

Thanks
Brian

It sounds like you might also be getting moisture from the walls and floor. In new construction a 6 mil. plastic vapor barrier is placed under a concrete slab floor.

Originally Posted by Brian Doyle

Hi all,

I’ve seen some forums on the site about ventilating unheated basements, but none seem to quite address my situation. Here’s my situation:
· We live in New Brunswick, Canada (climate on par with northern Maine)
· We purchased a summer cottage this past June that is really a ~45 year old small house with full basement. There is a porch that was added on that sits on the basement as well, and opens directly to the basement (open concept, no door).
· The basement is very damp. There is a built-in sump, but the lot is relatively wet.
· We planned to get external drain tiles redone, but the contractor did not get to it before the first snowfall, so now it’s on hold until the spring.
· The previous owner installed a 2-speed fan in the stairwell that exhausts air from the basement (he kept 1-2 basement windows open all summer). This kept the basement somewhat dry.
· So, since we are only using the home for the summer, I winterized the whole cottage (drained water lines, shut off all power, except to the sump, closed all windows, etc). We did this in early November.
I came back 3-4 weeks later, and this was the situation:
· I opened the door to the porch, and there was moisture on all the walls.
· The porch ceiling was blackened with mold.
· The exterior door, and the door to the main floor were covered in moisture
· The walls were all moldy
· In the basement (unfinished, no insulation), there was white puffy mold on the floor and wherever it could attach itself (shelves, etc)
· There had been a lot of rain and snow, and water was free flowing into the sump cavity
So, I know I have a mess to clean up in the spring. Hopefully the drain tiles (draining to an exterior ditch) will help reduce moisture. I expect that when the basement temperature drops below freezing, the mold will cease growing.
I figured putting an air exchanger in the basement and running it all winter might resolve the situation. Further research seems to indicate that these don’t work well in cold weather as the heat recovery unit (which I don’t actually need) will freeze up.

Does anyone have a suggested solution to my problem?
If you need more info as well, let me know.

Thanks
Brian

It sounds like you might also be getting moisture from the walls and floor. In new construction a 6 mil. plastic vapor barrier is placed under a concrete slab floor. The walls would receive a asphalt or bituthene membrane on the exterior face of the basement walls. It is time consuming to do this on existing walls and basement floors, but it will be worth it.

Something tells me this house has a history of mold. And Yes I might think about ventilating that basement but the real issue is the water "Free flowing" I actually saw a running stream in the basement of one house - came in under the stone foundation that was over 8 ft deep. (no kidding the stream was about 2ft wide and 6 inches deep. The real issue is how much moisture and can it be controlled - Hummm , Then there is the issue of the mold , can that be cleaned up (and no I don't mean just wiping it off the surface - I will guess it is deeper than that and will keep coming back - Maybe there is a health hazard ? If there is too much moisture you will have a rot issue in the structure as well.

It might be in your best interest to sell this money pit

Miss Cleo the psychic home advisers says - I see terrible things in your future
I really do not like the explosion of mold and see this as a real potential for human health hazard and remediation could cost more than the property is worth.

sorry , I hate to be Mr. Doom and Gloom but did you have this place inspected ?

I think you need to separate that wet basement from the porch with a tight door.
The fan was probably helping to vent the moist air out of the porch. The previous owner probably kept heat on thru the winter.
As for mould dying in cold weather, yes, it will go dormant and die back, but it will be right back with a vengeance at the first warmup.

I would recommend to wait until you have completed you perimeter drainage. Then measure the relative humidity.

Insure the contractor anti damps the concrete walls prior the backfill.
You can also use a vertical drip plain or dimple board systems.
The cost is slightly more and well worth the effort.

Delt-MS is one such system. It must be installed to the manufacturer's recommendations. No cutting corners.
Delta-MS.JPG
This will cut down any chances of water infiltration by/though capillary action and reduce dew point condensation, or sweating wall syndrome as well.

Once you have everything in place the whole system should slow down water that gets under the slab. Remember concrete is porous so moisture in brought into the air at the slab.

Once your system is in place think about conditioning the space if your have to. Keep the basement at 55 yo 60 f.

Hope that helps.

Mold growth will not occur when the relative humidity (rh) is less than 50%. Black and white molds are typical for the conditions described. 50%rh is hard to achieve in the cold months when the unheated basement walls are leaking and there is no warm ventilation air to remove the evaporated moisture. Also, extreme cold surfaces should not be condensing moisture. Insulate (vapor-tight) surfaces or lower the relative humidity.

1. You need to stop the inflow or infiltration of water into the basement.
2. Either: maintain a well-ventilated basement air space at all times or, seal it up tight and install dehumidifiers which will remove the moisture and add some heat. (This means also adding a door from basement to porch.
3. Hose the entire basement down with a strong bleach solution
4. Dry it out.
5. Ozone(7g to 14 gr O3/hr) the basement air space for 24 hrs then ventilate well.
6. Set up the Ping-Pong table and you are on your way!

MAS

OSHA’s and EPA's updated recommendations and suggested guidelines. The use of bleach as a mold disinfectant is best left to kitchen and bathroom counter tops, tubs and shower glass, etc.
Whether in its pure form or mixed with other chemicals, ozone can beharmful to health. When inhaled, ozone can damage the lungs. Relatively low amounts of ozone can cause chest pain, coughing, shortness of breath and lung irritation.

I am sure you intentions are well meant but I consider them best left to organic growth remediation professionals.

As with any mold remediation, first you have to find and stop the source of nourishment.

Originally Posted by ROBERT YOUNG

OSHA’s and EPA's updated recommendations and suggested guidelines. The use of bleach as a mold disinfectant is best left to kitchen and bathroom counter tops, tubs and shower glass, etc.
Whether in its pure form or mixed with other chemicals, ozone can beharmful to health. When inhaled, ozone can damage the lungs. Relatively low amounts of ozone can cause chest pain, coughing, shortness of breath and lung irritation.

I am sure you intentions are well meant but I consider them best left to organic growth remediation professionals.

As with any mold remediation, first you have to find and stop the source of nourishment.

Did my remediation tell the owner who should apply the sodium hypochlorite and specifically how to perform the remediation? Let's drink bleach and breathe ozone, shall we? I would not expect the owner to have his own ozonator and plan on living in the basement space for 24 hrs snorting up the ozone. Anything that will kill mold will also will also kill humans. Duh?

You will never eliminate the sources of nourishment load, you must reduce the moisture load.

MAS

FYI, I have had good results using a solution of water, vinegar and borax. No harmful fumes and does appear to have a residual effect on the wood surface.

Thanks for all the great feedback everyone.
So, if I take some advice from everyone, is this a do-able solution?
In the spring...
1. Clean up the mold (replace ceiling tiles, etc in the porch)
2. Install external drain tile that drains to the ditch (not internally to a sump)
3. Preferably install wall membrane when installing the drain tile

I don't really want to heat the basement in winter as it's mostly uninsulated (there is some 1" foamboard in places) and will cost me probably $300/month to heat.
All previous owners probably did heat the basement as it was their full time dwelling. We will only use it May-Oct.

So, here are a few more questions...
1. Should I do anything with the basement floor? It's concrete, except for the sump pit, with about 7' of head clearance.
2. What should I do about ventilation, if anything? Dehumidifier in summer? I thought about running the porch fan all winter, but I thought pulling in even colder air (-20 C to -30 C) might freeze the sump pump (I have it covered with a few layers of foamboard currently)

Thanks
Brian

Old houses are so much fun!

Good exterior waterproofing and drainage systems first.
Then re-evaluate.
Clean the interior, I agree with Vern, Borax is cheap and great and does not harm humans.
If the interior is still humid/damp and you feel the need to spend more $$$ then a dehumidifier running 24-7 may be needed. You can look for a small soar array to power the dehumidifier to be green....

If there is a lot of moisture coming up through the slab: find the low area of the slab and the are with the most moisture, dig a sump pit and install a sump pump; lay down 10 mil minimum plastic sheeting: lay sleepers on top of the plastic sheeting to lay a floor down on: lay the floor and leave an access cover over the sump pump; then let the sump keep the moisture pumped out.

Another way may be to also install what amounts to a wet vacuum running on a time clock, maybe 30 minutes on, 30 minutes off, 30 minutes on, etc., which would create a negative pressure below the plastic sheeting and actually serve to suck the moisture up and through the slab, blowing/pumping it to a drain some place.

You need to either stop the moisture from entering, or find a way to remove more moisture than is entering.

Originally Posted by Jerry Peck

If there is a lot of moisture coming up through the slab: find the low area of the slab and the are with the most moisture, dig a sump pit and install a sump pump; lay down 10 mil minimum plastic sheeting: lay sleepers on top of the plastic sheeting to lay a floor down on: lay the floor and leave an access cover over the sump pump; then let the sump keep the moisture pumped out.

Another way may be to also install what amounts to a wet vacuum running on a time clock, maybe 30 minutes on, 30 minutes off, 30 minutes on, etc., which would create a negative pressure below the plastic sheeting and actually serve to suck the moisture up and through the slab, blowing/pumping it to a drain some place.

You need to either stop the moisture from entering, or find a way to remove more moisture than is entering.

Jerry does have a good idea of using a wet vac - a little short on detail (unusual for him) the wet vac needs to be vented to the outside (might seem obvious but...) also if you do install a dehumifier I suggest something with a high capacity rated for low temperature and with an auto pump out - you will pump this outside too , not drain it into the sump.

Your clean up is going to be difficult (I know I used to have a commercial cleaning business and did flood and fire and mold remediation. The Ozone Generator (if you can borrow one will be your very tool) but if you get one be able to disconnect from the outside and ventalate the building from the outside for at least 6 hours after 24-48 treatment - then move the ozone generator and do it again) - Borax will work well , any drop ceiling - dispose of them, all drapes - remove and clean , carpet - dispose of .

Everyone is right - unless you can solve the moisture issue what is the point in cleaning up. if you can get some ventalation into the house now it would be ideal as long as you are power venting out as well. Winter dryness can do wonders ( I am liking the wet vac idea more and more here) along with a little bit of heat for the sump (anyone with an idea on that for Brian.

are you really sure you want to keep this property ?

Oh - BTW - stay away from the Bleach - it isn't good for you to breath too much of it in a confined location

There is a sump in place already if I am not mistaken..

It may be advantageous to locate the slabs low spot and rethink the basement slabs water management mechanics.

Bare with me.
I am taking as someone that worked the trenches applying self hypothesized/conjecture and personally remedy from any material I could read. One size does not fit all and too many cooks spoil the recipe. Hensforth, I worked alone. Engineers are asuste but give me a field trouble shorter any day.

In a good number of cases, the slabs drainage aggregate layer had become compromised over time due to soil mechanics and the out of sight / out of mind attitude by the many builders I worked behind solving their one size fits all attitude.

IMO: If water is the main culprit damaging buildings and affects human health as well an attitude and understanding of water control, not management, should be applied throughout the building stages.

It starts at the strata, then drainage and then at the material/additives for/on the foundation. Oversight by the builder is paramount.

Any whooo. I agree, a sump is required at the lowest spot.
What type is the question.
Not being able to see the site, I can not determine what would work best.

As a past builder, I would be planning a weeping basin for several reasons.
1: Soil mechanics and the properties age may have compromised the drainage aggregate under the slab. If there is any.
2: The existing sump may not be at the low spot nor be the best choice...
3: Where is the basement pump discharging?

A weeping basin: A weeping basin is a basin the is well perforated with 1/4" or larger holes spaced 4" inches apart covering the lower 3/4 of the basin.
The pump should be on a pedestal. A 2" patio block would be sufficient. This would protect the impeller and housing from getting clogged with any particular that entered the water control system.

The Slab: If the aggregate drainage layer is contaminated with soil particulate the pathway for water/air is basically restricted or even non existing. In this case, it may be advantageous in trenching a circumference twice the diameter and depth of a NEW plastic weeping basin.
If you can not find a weeping basin make your own.

Prior to placing in aggregate and leveling off the weeping basin and filling the rest of the void, line the newly exposed soil with road/highway construction geo fabric if the soil mechanics/make up allows. This will slow down migrating silt/soil particulate. I recommend, do not use a fine geo fabric.

About the soil mechanics of your lot, ask any excavator/excavation companies that work that area. Usually the/an operator is very kind and will help by telling you what he knows.

You will be fine doing the cleaning and restoration.
I agree with all. Once you control the water/moisture, then it's elbow grease and asking questions to the right people.

perforated sump basin..JPG

Originally Posted by Mark Sokalski

Did my remediation tell the owner who should apply the sodium hypochlorite and specifically how to perform the remediation? Let's drink bleach and breathe ozone, shall we?
The push back by some individuals donate within a civil debate to help someone they do not know never ceases to amaze me.

I would not expect the owner to have his own ozonator and plan on living in the basement space for 24 hrs snorting up the ozone.
I would not even recommend ozone.

Anything that will kill mold will also will also kill humans. Duh?
Did I or anyone say that?

You will never eliminate the sources of nourishment load, you must reduce the moisture load.

I am astounded by your redorec and blanket statements.
We live on a water planet.
I hope that blanket statements keeps you warm during any civil debates.

MAS

Sorry if my post was misinterpreted Mark.
I was not condoning, condescending nor was I being out and out rude.
Shame on you.
Didn't your mother teach you any manners?

Please debate or refer with dignity and intelligence please. We are all guests at Brian Hannigan's Inspection News.
I acted as you do now with Mr. Peck and other gentlemen not knowing better years ago. I fully admit I was wrong in doing so.
I am looking for civility after being ousted by members at InterNACHI. ARE YOU ONE OF THEM?

I am sure everyone means well.
I applaud everyone here.......well almost everyone.

In the world I live in Mark, the sky is blue, not everyone is gifted as yourself, THANK GOD, and homeowners for the most part DIY and relate to home inspectors as astute and listen to what they say and act upon their referrals.

Harry, its Jim. I was on a thread where a home inspector recommend I use ozone. You know where I can rent a generator? Ozone must be safe if the inspector said so.
Jim, lets ask Paul next door. He is always fixing something around his house.
Paul, you know where Jim can rent a ozone generator?
Guys, I have 3 ozone air fresheners in my home running 24/7. There great! I know a guy that rents them for flood restoration projects. No tax and no contract guys. What a steel!!!!

Sorry colleagues, you fight fire with fire at times.
Ozone is dangerous. That is not an opinion sir. EPA & Ozone

• Ozone is associated with increased mortality.

Breathing even minimal amounts of ozone can be toxic. Lung irritation, ozone poisoning, lung scarring, cancer and death are all health risks associated with breathing ozone. The EPA website lists twenty-six different scientific research articles describing the dangers of ozone inhalation and the use of ozone as an air purifier. This research has formed the foundation of the EPA recommendation against the use of "ozone generators."

I am sure there are green organic ways of working with mother nature.

Best regards Mark.
Robert