Step 4: Damp proofing and sealing the bottom boards

The fourth step in building YZY Kit Homes is to damp proof the building. Damp proofing involves damp proof course installation around a perimeter of the building and sealing the bottom boards. Damp proofing is an important step and prevents the building from moisture damage and penetration coming from outside.

Damp proof course installation

Damp proof course installation is a fairly easy step. It takes about 30 min for a smaller buildings and about an hour for larger kit homes. Follow the 3 steps below and watch the video to see how it’s done.

  1. Determine how wide the damp proof course for your building should be. Use 150 mm damp course for buildings with 45mm and 60mm wall boards, and wider for thicker walls.
  2. Lay out damp proof course overlapping all the corners. Cut it 200 mm longer in the corners and then trim it to size as you go.
  3. Nail the damp proof course to the subfloor, every 600mm along the perimeter and extra nails in all corners.

Expert’s tip

To get a nice crease so it’s in tight to your yellow tongue flooring, we use a block of timber that’s about the same thickness of our yellow tongue, which is 18 mm. Then bash it into the corner which creases the flashing really nice and tight. This way your damp proof course fits in really square into your floor.

Watch the video below for detailed instructions.

Sealing the bottom boards with timber protective emulsion

That is another one of the most important steps before you get too far involved. So grab the bottom boards, locate which end halls are going for electrical and hold down bolts. Brush a preservative on underside just to stop any moisture penetration that comes from the top of flashing installed around the perimeter of the building. It is also a good idea to seal the end grains to stop the checking and cracking, the first board is the most important to put a sealer on.

Expert’s tip

Waterproof the flooring of the sub-floor with the flashing/damp proof course around the perimeter. Apply an even coating of CN (Copper Naphthenate) timber protective Emulsion to the lower wall-boards. Follow the timber preservation chemicals manufacturer’s instructions. Please note, it must be applied sparingly as it might show through any internal or external paints.

The next step is to fix the first layer of wall-boards to the sub-floor. The list of all building steps can be found on Builders Guide page.