Existing building without weather resistive barrier
I have been asked to look at converting an existing 20′ x 32′ “tool barn” in to a finished structure. The existing building was built with the blessing of the local building department less than 10 years ago and has a stepped parimeter foundation due to a slight slope, T-111 siding and a dirt floor except for one corner that has a slab poured to create a standard 8 foot ceiling height. The idea would be to pour a concrete slab throughout the rest of the building and finish it off. Here’s the catch…there is no tyvek, building paper or any weather resistive barrier behind the T-111 siding. It is open to the inside and there is evidence that water has blown up through the Z metal flashing as evidenced by staining on the back side of the plywood siding that corrosponds mainly to the vertical groove pattern on the exterior of the siding. Building paper alone would not have prevented this but it would have kept water off the studs. There is no decay or rot of any kind. We live in the Gold Rush country of the Sierria Nevada foothills which is pretty dry so this ocasional wind driven rain problem hasn’t been much of a problem…so far.
My question is what to do in place of or as a subsitute for a weather resistive barrier? The finished structure will probably be a day game room or possibly a guest bed with water, power and septic hook-ups. With out removing all the siding I have been thinking of spraying a good coat of paint on the raw frame and backside of the siding as well as caulking where the Z metal an vertical grooves meet.
Any other sugestions?
Thank you,
Ross Welsh
Replies
Are you going to insulate it?
The real solution
is to treat the T1-11 as sheathing, put felt over it, and install new siding, window flashing, etc.
You can't stop water from coming in where it's now coming in, and enclosing the walls will eventually cause water damage.
insulate and finish
The home owner and I have not gotten into any detail on this project because he has been out of town on business but we will be meeting in about a week when he gets back. I am doing my homework now so I will be prepared. I would imagine that he would like to insulate and certainly enclose the walls; all of which change the situation. The Z metal situation is typical; it lies at the top plate / bottom of gable area and also 8 feet below that where the 8 foot tall siding ends and some fill pieces lie below the floor lie to fill in the stepped foundation area. The problem is only at the gable ends of the structure so starting over or using the siding as sheathing would not be very costly. This morning after reading your responses I also thought of lifting the siding above the Z metal and sneaking a substantial flashing up higher. This could be done mainly from the inside.
Thanks for helping me think this thing through
Ross
Bottom line is
that the building was intended to be a garage without insulation or drywall, and was built as such. Too bad it's so hard to sneak Tyvek in behind finished siding!