Disappointment is the emotion most prevalent over the last week. Now that all the floor assemblies are installed over the basement, it is dark – really dark. So last Thursday I finally installed some construction lighting in the basement and I had quite a shock when I turned them on.
MOULD! Or more specifically staining fungi.
All of my engineered beams have fungi stains all over them. One has gotten wet from a leak in the tarp above, but the majority of them have never seen any form of bulk water. After all of the time and money I have put into keeping this place dry during construction, this was a huge disappointment for me and was quite puzzling until I looked into it a bit deeper.
I got out my professional moisture meter and I was seeing wood moisture readings as high as 30-50% in the beams (higher on the beam that has seen actual liquid water) and only 15-20% on the ‘real wood’ structures. I then got out the Psychrometer and it registered a whopping 84.5% RH at 5.7 C. What was worse was that the dewpoint was around 4 C (it is currently 3C as I write this).
So it appears that the offender is below and not above and this caught me completely by surprise. I have spent all this time trying to keep the rain off, I paid no attention at all to the monster lurking just below the surface of the gravel. You see, the dwelling is built over a large shallow lake, at least that is how the water sitting in the gravel drainage plane acts. And of course last weeks power issues, caused by a pump that was shorting out, did not help things. I ended up with 4″-8″ of sitting water depending on what thickness of gravel was present (not a problem directly as only in contact with gravel, concrete or ICF, but contributed to even higher humidity I am sure). Took the rest of the day to pump out once the pump was replaced. It is the humidity caused by all this sitting water that I am fairly confident is wetting up the beams.
So why is the real wood drier? Good question, and one I do not have all the answers to yet. For one, the real wood is a lot more permeable, so it would dry much faster than the beams (that are basically wood chips pressed into a rectangle and held tight with glue). But beyond this, I am just not 100% sure (but will try to find out). Unfortunately, the glue which not only makes the beams less permeable, also is an excellent food source for fungi.
While this has absolutely no effect on the bearing capacity of the beams (would need rot fungi over years for structural capacity to be effected or for the wood to become 100% saturated for months until the physical binds of the glue break down), and in most homes under construction this would just be typically ignored or at the most painted over, I have fungi allergies and really do not want this stuff in my home. So I will first remove the staining and then apply a product to kill the mould and prevent re-growth. I was passed on a recommendation to use Concrobium Mold Stain Remover. This is not the consumer stuff you find at the Big Box Stores, but a professional product I purchased from Sycorp Environmental. I have also bought Concrobium Mold Control.
While I wait for their arrival, I am also going to try and attack the problem at the source and combat the high humidity in the basement. Ultimately this is controlled by the concrete slab and sub slab poly, but these are many months away from being installed (I have to first complete the basement plumbing). So I am going to look at putting down a temp poly sheet over most of the gravel surface. To prevent the poly from being destroyed by the gravel, I am going to pick up some free coir mats that come from a company that recycles beds. I should be able to get enough to cover the gravel and then again cover the plastic once put down. This will protect the plastic from both sides and hopefully allow the poly to be used again in the final installation below the concrete slab. Not only should this dramatically lower the RH% in the basement, it should also reduce the build-up of condensation under the tarp. I can then look at mechanical humidification if I still have a problem would would not be economical or effective if I did not first substantially reduce the humidity load.
Otherwise it has been pretty slow at the site over the last week. I just cannot get motivated enough to go over on the wet/cold days and as luck would have it have had appointments and Christmas meal engagements with friends on days that have been clear. But I have forced myself to get there a few hours here and there and have now installed construction lighting in basement, removed the curb forming around the garage south and east walls, started to clean up the floor deck, done a lot of tarp patching to reduce the puddles I get scattered about, and today started building the supports needed to rehang the tarp over the garage so I can dry out the foundation walls and finish the water proofing.
I will get the garage tarp put up and a bit more cleanup done this week but will then take some time off for Christmas. In the week between Christmas and New years I will concentrate on taking down the shoring under the suspended concrete slab and returning to vendor and then if dry enough, applying the torch on membrane to the top of the foundation walls along the south and east garage walls.
With that I would like to wish you all a Blessed Christmas and New Years. Hope you are surrounded with joy, peace and family love!
Thanks for visiting