Basement Finishing Details - The Province, Sunday June 12th
June 13, 2011
SEVENTH IN A SERIES
The proper way to insulate and finish inside concrete walls is in the following manner:
Identify the outside grade level, and then transfer this measurement to the inside of the concrete wall. From that point, use a level and draw a line on the wall 6” above the grade line all the way along the interior of your concrete wall. This now becomes the height of your polyvapour seal – 6-mil polyethylene (available in 10 foot widths). Spread a bead of acoustic adhesive along this line (acoustic adhesive is available at your local building supply store in tube form). This adhesive will stick your 6-mil polyethylene to the concrete. Apply the same adhesive down the inside of the concrete wall and out onto the floor. This stops any moisture emanating from the concrete to the wood studs.
Build stud walls that are 1 ˝” shorter than the actual wall height. This allows the walls to be tilted up and put into position and you can then screw them to the underside of your joists up tight against the concrete wall. Cut Styrofoam or polyurethane foam in blocks (1 ˝” thick) and position them every 2 feet along the bottom of the stud wall. Pound a 4” common nail (it does not have to be a concrete nail) through the bottom plate and the foam block and into the concrete, stopping when your hammer rings. The wall will remain in place because it is now screwed to the underside of the joist and nailed into the concrete floor.
Now you are ready to prepare the wall for insulation. If there is a pony wall above the concrete, remove any polyvapour seal from this wall. Stack R12 insulation batts behind, lying on their side above the concrete wall and the joist above, thus covering the pony wall section if it exists. Put insulation batts in green garbage bags making insulation pillows. Put these “pillows” in the joist header areas (where the joist runs over the plate to the outside joist fascia). Run insulation batts between the newly studded wall from the joist line to the floor.
Finally, take the extra polyethylene vapour seal that is lying out on the floor (the excess of the 10 ft. width) and bring it up around the studded wall as far as it will reach and staple it in place. Staple another piece of polyethylene from the top area onto the underside of the joist 12” out from the studded wall bringing it down the wall to meet the polyethylene coming up from the floor. Overlap them and seal with acoustic adhesive. You have now totally encased the finished interior framing wall and will prevent any moisture that may emit from the concrete to get into the wood fibre and/or insulation causing a musty odour.
Proceed to drywall or panel. Now no moisture will ever get near a wood fibre. If there is ever a crack in the wall or floor, the moisture will run up against the polyethylene, run back in behind and out onto the floor and will be identified at the floor line rather than up in behind your panelling or drywall.
Be Sure to Check Local Building Codes and Permits:
To begin, you must obtain a building permit if you intend to alter the structure of your house, increase the size of windows or exterior doors, or change the occupancy — for instance, by adding a self-contained apartment suite. The building permit ensures that the changes respect minimum standards of health and safety. To make a good living space, a basement should be high enough to permit ceiling fixtures or fans with space beneath for a 1.8-m (6-ft.) tall person to stand. Most municipalities require a height of 2.1 m (6.8 ft.) from finished floor to ceiling before they will issue a building permit, which is also the minimum height required by most electrical codes for a ceiling light. Ask your building official what minimum heights are required.
Most basement floors start off as a cold concrete slab where dampness and cold can enter the floor from the ground beneath it. Even the best-designed basement may experience a serious leak, spill or flood. It is prudent to install water-resistant or impermeable floor and wall finishes, with ceramic tile, carpet or a luxury vinyl such as Karndean
. All are durable choices that are easy to install over concrete. Solid-wood flooring is not recommended for basement applications because moisture levels can cause buckling and warping, but engineered is a suitable alternative. Building codes require an occupied basement in a new house to have a moisture barrier, such as polyethylene, beneath the slab. The Delta-FL membrane, which is available through Basement Systems
, is a dimpled membrane that allows concrete to breathe and also serves as a vapour barrier, which in the end means a warmer floor. Once the Delta-FL is in place, you install your sub floor on top, and then finish with your flooring.
Sound Proofing and Noise Control
Whether your lower level is a secondary suite or media room noise can travel throughout the household. Control sound transfer by soundproofing interior walls and ceilings. Insulate interior walls and choose drywall that is soundproof. QuietRock available from Dryco
drywall is visually indistinguishable from standard drywall, but it is engineered to dampen noise.
More to come next week. This article was published in The Province
newspaper, Sunday June 12th.