I just finished a 3 month remodel of my son’s 70 year old house. He was having some water problems … the house is on the hills of Berkeley and the water was coming into the laundry room which was dug into the hill and which was under the garage, and he was also getting water in a utility room which was under the master bedroom … again dug into the hill.
I think we solved the water problems just fine but just as we were packing up to leave we got a rude surprise. Downstairs, in the back, is a den which we were using as a temporary bedroom for one of the guys. He had put down the futon at the start and used it to sleep on for the 3 months. When he folded the futon back into a could he saw mold on the underside of the futon. That explains why he was sick on and off for the bulk of the schedule.
That room is over a crawl space that does not have any vents. The dirt floor is wet but no standing water. I’m thinking that the moisture is gravitating up into the flooring and the rug got damp underneath the futon because the bed coverings didn’t allow for air flow.
The question now is how to fix the room and how to fix the moisture problem in the unvented cxrawl space. We’ve thrown out the futon mattress and I’ve told my son to throw out the carpeting in that room along with the carpet pad. The only access to the crawl space is a door on the back side of the house (maybe 2 feet by 2 feet). I’m thinking we should put a fan in there, with the door open, and also a dehumidifier. How many vents and what size should we add? Would it be a good idea to add a permanent dehumidifier, or a permanent fan? What should we do the room to kill the current mold? Should we do anything in the crawl space to kill existing fungus? Any warnings on what we should do, breathing wise, while in the crawl space? Just masks or anything more industrial strength?
Lastly, is this an insurance issue? We didn’t do anything, pro or con, to ameliorate this condition. We didn’t smell anything and the room didn’t seem damp.
Thanks in advance for any help here. The holidays are coming and this room will be used for sleeping.
John
Replies
First, make sure you have effectively dealt with any water infiltration problems with respect to the house and crawl space.
Then, you can get rid of mold with a mixture of clorox (bleach) and water. Be careful though, chlorine gas is nothing to take lightly.
This web site has some stuff for you to read: http://www.apawood.org/level_c.cfm?content=pub_searchresults&pK=bett&pT=Yes&pD=Yes&pF=Yes
Read two articles: Foundations and Mold and Mildew.
In the foundation article, it gives the formula for the required ventilation which is basically floor area/150. (assuming you decide to ventilate the crawl) BTW - is the HVAC system and/or ducts in the crawl space?
You can probably do the initial drying by renting a fairly high powered blower, but you are gonna have to get some cross ventilation going some how.
Once you get the crawl space dried out, you want to cover the dirt floor with plastic, and perhaps even run it up the crawl walls and staple it to the floor system's mud sill, especially on the side that faces the hill. Over lap all joints 6-12" and seal or tape them. Glue the plastic to the walls. A product that is much better than the run of the mill polyethylene is called Tu-Tuff. You can find it on a web search. In addition to being more durable than regular poly, you can glue/tape it better than regular poly. Installing the plastic is very important.
Thanks for the input.
The crawl space I'm referring to does not have any HVAC ducting. The rest of the downstairs is on a slab, but this room is over a dip in the land which the original builder evidently chose not to change.
As part of the project we used a producxt called Xypex which is a cement like product which is supposed to migrate into concrete and create crystals which effecdtdively block moisture. We used this in the area under the garage to prevent moisture getting into the existing laundry room. We also diverted a downspout so that the roof water doesn't go into the front garden (next to the laundry room), and we also put a french drain into that garden (actually it's a stepped garden, in the hill) so that ground water won't be up against the foundation in that area.
We also cleaned and caulked all areas on both sides of the house where the concrete steps had pulled away from the foundation. This should prevent ground water from getting into this area. Lastly, we took the entire front of the house which was a mixture of garden areas up against the front of the house (3 feet wide) and very bad old concrete which was not remotely level and poured a new concrete front patio area about 12 feet wide and along the entire front of the house. This patio slopes away from the house and also slopes toward the side of the house, so that all rain water will flow to this side and away from the house. This should effectively remove all water from the front.
My guess is that we've solved water entry problems. Inside, we installed bathroom fans in both bathrooms to remove excess moisture. This isn't related to the topic of this discussion, but I wanted to mention it.
I think what we'll do is use detergent/fwater to clean up the room for our immediate problem, which is sleeping over the holidays. This will be after removing the carpet and pad, as they probably can't be saved.
As to the crawl space, I'll have to get in there to see how bad the actual mold problem is ... which is undoubtedly bad. I'm concerned about using some sort of chlorine bleach because of the lack of ventilation in that area. And the person doing the cleaning will be crawling around, exerting themselves, which causes more deep breathing.
I like the Tu-Tuff idea and will pursue doing that as a part of the permanent solution.
The thing I'm unsure of is whether we should install vents. I don't like the idea of no venting. Admittedly, that area is much more moist than other areas of the country, and there's no way to prevent the vents from bringing in moisture. Is thre some sort of way we could mechanically (some sort of fan/dehumidifier setup?) remove the moisture ... which would probably involve installing an inlet vent to bring in air and an outlet vent to exhause moist air? What I'm getting at here is what should we do to the area other than install the Tu-Tuff to prevent future problems.
Thanks.
John
your probably right about the moisture migrating up - in fact, in my area if I see a lot of mold growth on the bottom of the roof sheathing I'll probably see a wet crawl space!
As noted, a necessary step is to keep as much water out as possible, and in your climate ventilation is likely the answer. Consider checking with an experienced home inspector - they see a lot of similar situations and will likely know what will be best in your area.
The various experts on mold remediation seem to be moving away from recommending bleach for cleanup - I believe because of potential health hazards from the fumes during cleanup.* (My own, limited experience has been that for small, washable areas, at least, hot water and automatic dishwasher powder detergent does a good job, but there may be better products - some borax based detergents have gotten recent mention by the experts.)
Check out the EPA web site: http://www.epa.gov/iaq/molds/moldguide.html
The NYC health Dept also has a lot of information which is often cited for expert advice: http://www.ci.nyc.ny.us/html/doh/html/epi/moldrpt1.html
---------------
* See, e.g., the Building Scince Corp site: "Do not sand wood in an attempt to remove mold: use soap and water and elbow grease.
Bleach is NOT recommended as part of the clean-up.
Why? Remember, clean-up means mold removal. To remove
the mold, it is not necessary to kill the mold. Bleach is an
irritant to eyes, skin and the respiratory tract (nose, throat and
lungs)." (at two pages linked from its mopld resources page: http://www.buildingscience.com/resources/mold/default.htm )
BSC is always worth listening too, they are highly regarded by everyone I know and respect.
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Edited 12/19/2003 2:56:25 AM ET by Bob Walker
John:
Another thought re crawl space ventilation - in your situation, you may want to think about permanent mechanical ventilation in the form of a small fan or blower. If you do a web search you will find that they sell devices made just for this purpose. Some have a built in humidistat.
Matt
PS: I have found the diluted clorox thing to work in actual practice on several houses. It is a very nasty job, but it is not clear to me how soap and water would be used to clean a dirt crawl space floor.
I don't think you should put a fan and a dehumidifier in there, with the door open, unless you want to attempt dehumidfying the entire Bay Area. Since there's no standing water, I'd do the Tu-Tuff first, sealed at the seams and to the top of the foundation, then I'd run the dehumidifier. Running the dehumidifier with no plastic on the ground will likely be futile as the ground can probably supply an unlimited amount of moisture. After you've gotten rid of the existing moisture (be prepared for flooring and moldings in the room above to crack as they dry), I'd suggest stopping for a year or so and simply observing. Did these measures succeed? If so, then I wouldn't vent, which in my experience is just as likely to increase the moisture level in a crawlspace as to decrease it.
"...I wouldn't vent, which in my experience is just as likely to increase the moisture level in a crawlspace as to decrease it."
Good point - One I forgot to mention. But I also agree that outside venting of crawlspaces isn't a good idea.Bumpersticker: If the kid is an honor student, he must not really be yours.
>>do the Tu-Tuff first, sealed at the seams and to the top of the foundation,
In my experience, in MY area, bringing the vapor barrier to the top of the foundation can lead to significant decay of the sill plate, particularly in older buildings where the sill plate is not treated lumber.
It doesn't happen all of the time, but of the times I seen the vapor barrier brought that high (maybe 75-100 times), I'd say 10=15% have varying degrees of decay in the sills.
_______________________
Tool Donations Sought
I'm matching tool donors to a church mission to Haiti - we're shipping a bus converted to a medical facility in January (we hope) and can fill it with clothes, tools and all sorts of stuff needed in that poorest of all countries. A few hand tools or power tools can provide a livelihood for an otherwise destitute family. Please email me if you have tools to donate.
Thanks to Jeff and David and Jim for their offers!
I posted a related question (pasted below) a few days ago and got almost no response...probably just got lost...but any input on my questions would not only help me but also anyone else in this situation. By the way TOMMORROW is the day DW and I are going down there to deal with this issue, and I'd like to do it the right way the first time!
Question regarding vapor barrier detail for a sealed crawl space:
Facts:
Pressure Treated Wood Foundation, SE Minnesota, 8" - 12" pea rock footing with 4" corrugated perimeter drain embedded, 4 foot frost wall of 2X8 .60 PT on 16" centers, 1/2" plywood .60 PT exterior sheathing. Back filled exterior 2 -3 ' up from footing plate with pearock, remainder clay-loam mix. 6 mil moisture barrior protected by 1" bead board on exterior. Exterior grade sloped away from foundation.
Interior back filled with clay-loam mix (whatever was there) to within 24" from bottom of floor joists.
6 mil fiber re-enforced poly vapor barrier applied to dirt crawl space floor. Insulating stud bays with unfaced fiber glass. 2" rigid foam blocks fit between studs providing separation between dirt and FG
Question is, should I:
(1) extend the vapor barrier on the floor all the way up to the bottom edge of the rim-joist and not seal it to the foam blocks?
(2) as (1) above but sealed to the foam?
(3) terminate the floor barrier at the foam, and run a separate barrier down from the rim joist, tucking under the floor barrier?
My concern, of course, is to prevent moisture from both the dirt floor and whatever might get through the foundation wall, from creating moisture (mold) problems in this crawl space, OR from migrating up through the FG in the stud space and causing problems there?
Trying to find a balance between sealing against moisture while at the same time allowing moisture a relatively harmless escape route...like back into the dirt.
Sorry, didn't see that first message post.
I don't see a lot of wood foundations in my area, so I don't have a base of direct experience to base a recommendation.
If I understand the description, because of the exterior moisture barrier, I'd consider not using any vapor/moister barrier on the inside to avoid trpping moisture inside the foundation itself.
As to that interior backfill.
Do I understand you to have said that dirt backfill was added inside the crawl? Piled up so the bottom 2 feet or so of the wood foundation is buried?
I have some real doubts about that - even .60 treated lumber isn't rot proof - it's just more rot resistent than other wood products.
I'd do some intensive research on that approach. Maybe it's OK but I'd want the experrt opinions on something like that.
& I wouldn't accept "that's the way we always do it" from the contractor. This method hasn't been around long enough for any sort of track record to have developed for such a technique.
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Tool Donations Sought
I'm matching tool donors to a church mission to Haiti - we're shipping a bus converted to a medical facility in January (we hope) and can fill it with clothes, tools and all sorts of stuff needed in that poorest of all countries. A few hand tools or power tools can provide a livelihood for an otherwise destitute family. Please email me if you have tools to donate.
Thanks to Jeff and David and Jim for their offers!
Thanks, Bob.
Pretty much followed the specs in this publication:
http://store.southernpine.com/images/ref400.pdf
I think what I'll do is just staple, not seal, the edge of the poly to the foundation and then keep an eye on it. I installed permanent light in this crawl for inspection purposes.
FWIW, I did plumbing on several houses with PTW foundations in this area 25 years ago and still know the owners of a few of them...one I inspected recently showed no signs of rot.
Thanks for all the help, guys. I think I've got a start on how to remediate this. I especially liked the links to articles ... which I printed out for both myself and my son to read.
John
Why not insulate exterior walls to below frost depth (check with local building dept), poly ground and walls properly and heat the crawlspace....or did I miss something
Bill from beautiful British Columbia.
John, I work with insurance adjustors on a regular basis. Call yours before you try to abate any mold yourself. It dosent matter what caused it. Its there and they gotta fix it. Mold eats wood also. Depending on your policy, they could pay for code upgrades ,vapor barriers,ect.. They will test first, then ,if its the bad stuff ,send an abatement contractor. The area gets isolated (sealed) ,followed by sandblasting. Triggerski
I'd agree that's a concern. My guess is that it might relate to the amount of foundation exposed above grade. The greater the amount above grade, the greater the chance for moisture to evaporate through the foundation.Andy Engel, The Former Accidental Moderator
Good point - I haven't paid particular attention to that aspect, but most of the older crawlspace houses in my area don't have much foundation exposed above grade on the outside.
_______________________
Tool Donations Sought
I'm matching tool donors to a church mission to Haiti - we're shipping a bus converted to a medical facility in January (we hope) and can fill it with clothes, tools and all sorts of stuff needed in that poorest of all countries. A few hand tools or power tools can provide a livelihood for an otherwise destitute family. Please email me if you have tools to donate.
Thanks to Jeff and David and Jim for their offers!
Andy:
RE weather to vent the crawl space, my thinking was that 1) Berkeley California I would guess has a relatively low average relative humidity. Maybe I'm wrong on that? and 2) A sealed crawlspace still needs some ventilation, weather it is via some kind of blower moving air from the house to the crawl, or an actual HVAC supply duct in the crawl. Correct? This introduces conditioned air into the crawl, which in tern, causes air to move from the crawl to the homes interior. Not sure this is the thing to do if there is a mold problem in the crawl...
Bob:
Good point about stapling VB to the sill plate. I can see how that could cause rot. I guess it might be better to run the VB part way up the wall (at least above grade) and glue it there. I'm talking about masonry foundations here - not the PT wood. I didn't make any statements about the PT foundation, as I have no experience in this area. (never even see one) I guess you get exposure to all kinds of construction techniques in your line of work...
Matt
Berkely is on the east side of San Francisco Bay, so it tends toward the damp, I believe. At least that seemed so in the bits I've visited. Assuming that the dirt is sealed off with plastic, and maybe even the walls insulated, then having a heat duct blow a bit into there likely wouldn't hurt anything and might do some good. I'd be content though with sealing and a dehumidifier. Who cares if the air in a place you never go is stale, as long as it's dry?
BTW, I do believe the whole mold issue is overblown. Yes, there are some severe circumstances where some species of mold can be dangerous, mostly to people with already-compromised immune systems. I think that the exposures most of us see are at worst uncomfortable. The bigger worries with most damp crawlspaces, IMAO, are the ick factor, the smell, the potential for overzealous litigation, and the potential for rot. Nonetheless, there is little but good to be had by drying a damp crawlspace. Andy Engel, The Former Accidental Moderator
I was up in your hills recently visiting Cal w/ my high school graduating daughter - beautiful country is it the architect Maybeck ( or the like ) that has so much fine work there?
all good stuff and a few more things to chime in with - those hills nearby are more verdant than most of the rest of the state ( esp to the south ) but definitely not wet ground you have all the hillside away from the foundation? or good drainage to alleviate water pressure, back up at wall?
dehumidifiers generally do not work if the temperature cannot be maintained at 60 degrees or above * something that does work great is an Air Dryr / mildew eater app 14" diameter * said to use equivalent of 40 wt bulb * available at most boating supply houses and maybe a GI Joe near you * they do plug in and do not need "new air" to be successful $35 - $45 / unit * get two & put them to work after covering dirt and washing mildew areas
Yes, it's a beautiful area. Both of my sons went to Cal as did my daughter-in-law. I'll have to check out your suggestion as to the device you mention. Worth checking into.
It'd be next to impossible to actually heat this space, as the heat duct is in the ceiling of the room above. Possible, I guess, but not sure it'd make sense. (This is to answer the question from the British Columbia guy.)
Lots of good suggestions here, and I appreciate everybody's input.
John
I whole heartedly agree with you on the mold thing being overblown. When I go in a crawl space to bolt up a deck or something, my main worry is spiders. Guess I'm just a wimp that way, but a little gross looking growing stuff never bothered me unless it's in the fridge :^(. On the other hand, not sure I'd want a large amount of it inside my house, although 15 years ago if one saw mold inside, the comment would be - "must be a leak or not enough ventilation". From there the conversation would center on fixing the problem, not belaboring the symptom.Matt
Thanks. I think you've pretty much covered one of the questions I had when I replied to the first responder.
Did I say that I hate old houses? This house had knob and tube wiring and lots of other weird stuff that made the project "interesting". This was a nasty surprise at the end. Sigh.
John