Sill plate treatment
Vic8
| Posted in General Questions on
Hi,
In my basement I have double 2×6 sill plates sitting on a CMU foundation. There is no gasket between the CMU and sill plates. After a major rain, I notice the sill plates can be damp. The house was built in 1964, and the sill plates currently have no rot. I cannot tell if the sills were pressure treated.
Out of caution, I’d like to preventatively treat them to prevent future rot, and am confused by the various options I’ve seen online – which are listed below. Any advice or thoughts on what the best option is to prevent future rot (besides just installing a gasket) would be much appreciated! Note: I only have access from inside the basement, the exterior is behind brick veneer.
1. Borate rods (if recommended, what brand and where do you buy them from?)
2. Spray bora-care w/ mold care
3. Copper coat.
GBA Detail Library
A collection of one thousand construction details organized by climate and house part
Search and download construction details
Replies
How's your grading around the house? Code requires a minimum of 6" fall over the first 10' around the building. Directing water away from your foundation is a very good idea.
Here's a good detail from FHB:
I would try to regrade around the house to help water to drain. All ground around the house should slope AWAY from the foundation wall.
You can retrofit a capillary break to an existing structure by lifting the wall very slightly in stages and sliding in pieces of HDPE between the top of the masonry wall and the mudsill. This is not as difficult as it sounds. This will be a huge help to protect the wood if the wood is damp due to water wicking up through the masonry foundation wall.
Lastly you can put a rot inhibitor on the mudsill. I've used Copper Coat for this myself, but remember that you can't apply that coating to the underside of the mudsill, so you won't get good protection the way you would if you had a pressure treated board in that location. Copper Coat is better than nothing, but it will be less beneficial than the two things I mentioned earlier.
Bill