Addition

[Mofu]

Our home has a small addition (10'x12') at the rear of the house which was not closed off at the base properly. Currently, the north side of the addition is attached to the house and the south side sits on a concrete foundation while the east and west sides are wide open at the base (i.e. if you get on your knees you can see right under the addition and through the other side)

Pics:

The addition is cold in the winter (we live in Winnipeg, Manitoba Canada where -30C or -22F is common) and looks like hell outside so I would like to finish both sides properly.

My question is, what is the proper way to close the east and west sides off? I was thinking about framing it with pressure treated lumber, insulating and finishing it with stucco or vinyl. Does this sound correct? Is it necessary to vent this space on both sides or is one vent ok?

Any feedback is much appreciated.

TIA, Curt

[tbasc]

The prefered way would put as little wood in contact with the ground as possible. Consider fiber cement panels with pressure treated wood frame on top and on two sides. The side frames should be held 6 inches off the ground. The ground in your photo looks dry, so you might get away with very limited vents. I would strongly recommend a vent on each side for cross venting. You might investigate attaching the panels in a way that allows venting around the panel edges.

TB

[borgunit]

Treated wood should have no issues with touching the ground. I would put a vapor barrier between the dirt and the living area though. The reason for vents is to dry out the space, but the humidity in the space is the same as the outside air and moisture constantly comes through the ground. Vents are optional, but neccessary if you do not place a vapor barrier on the soil. I would dig down far enough to retard any creatures from going under your "walls". Build a perimeter with treated wood. Insulate the inside of the perimeter with some solid foam insulation and then lay down a vapor barrier on the inside soil and up the inside perimeter walls. Make sure to "seal" (silicone) the joint between the barrier and where it comes to the living space joists. Just my opinion. Good luck.

[Colbyt]

That would work. Should be good for 10-15 years.

Since this is your home I would prefer no ground contact with wood even if it is treated. Could you pour a baby footer (3-4" deep) using concrete mix in a bag or dig out a place some 4x8x16 solid blocks in the ground before you use your treated lumber. Should be good 20-30 years.

Also keeps pets or critters from digging under the house.

Best wishes

Colbyt