Weekend project: Window of opportunity

Justin Newcombe's new French doors. Photo / Natalie Slade

Justin Newcombe finds replacing windows with French doors is a piece of cake - if you follow the instructions.

I'm replacing an existing set of windows with a set of timber French doors. I'm actually an indoor-outdoor flow building virgin, so a lot of investigation has gone into making sure I get everything right.

The first stop was to meet the very helpful Ian McCormick, building control manager at Auckland Council. Under new regulations, he explained, if the proposed doors are to be installed in an existing opening of the same width, a building consent is not required. Of course, all building work must still comply with the building code, which I quickly found here.

To install doors that exceeded the width of the existing windows I would also need a lot more expertise, so deciding to stick with the same-sized opening became a no-brainer. The other information I needed was about the joinery itself. I found this on the website of my local joiner, Westpine, who provide all the detailed drawings of the joinery cross sections and the flashing details to give me a clear idea of what I needed to do.

To cut a long story short, I ordered a set of their pine doors (which come complete with framing), got a great price on glazing, a delivery and heaps of good advice.

Once I had the cavity for the doors prepared I took a trip to Bunnings to pick up framing timber a couple of weatherboards, scribers, paint, soakers, etc and was ready to go.

All-in-all it was a pretty easy process but having an experienced builder on hand is a good idea if you haven't done this before. After all, you are cutting a massive hole in your biggest investment - your house. Since my house has had a good 60 years without leaks, I don't want it to start now.

Step 1

Do lots of research and get help if you're a first-timer. There are many variables and what may be appropriate in my case may be unorthodox or inappropriate in your place.

Step 2

Remove an internal architrave to give you the external width measurements of the actual window frame and the distance from the top of the frame to the floor. Also measure the depth of the wall (which is usually the depth of the window frame) and take this information to your joiner to discuss the design and details of your doors.

Step 3

Remove the existing window by removing the architraves and scribers. Use a reciprocating saw to cut the nails fixing the window frame to the building. I also had to trim the ends off the window sill. Then carefully lift the window out.

Step 4

To complete the cavity for the door, use a level and a pencil to mark out from the bottom of the window cavity to the floor.

Before you cut into any walls, check for power cables, electric plugs and water pipes. If you are in doubt, consult any house plans you may have or carefully remove any gib to check.

Cut the weatherboards with a skillsaw. Use a craft cutter to score the internal plasterboard and remove it. Remove the internal framing.

Step 5

Prime the outside framing that has come with the doors.

Step 6

To prepare the cavity for the door, measure the width and height of the door then measure your cavity. In my case internal framing is required to make the cavity the right size for the door, but in some cases a set of jambs will be all that is required.

I used h3.2 kiln-dried pine.

Step 7

Wrap the new framing in builder's paper and tuck the ends under the existing builder's paper between the framing and the weatherboards. Re-clad the outside making sure you either install or allow for installation of the top flashing.

Any weatherboard joins need to have exposed ends primed.

I also adhered each join with No More Gaps.

The join needs to be covered with a soaker, a piece of galvanised metal shaped to fit around the weatherboard to waterproof the join.

Step 8

Using bitumen flashing tape, line the top and sides of the cavity hole in the wall, making sure it overlaps the top of the sill flashing, which should come with the door and is like a bottom flashing.

Step 9

Once the cavity is lined insert the door. It should fit snugly.

Make any necessary adjustments. I needed to reduce the width and adjust the angle of the sill with a chisel.

Step 10

Fix the doors in place by nailing the frame internally to the framing of the building. Use jolt head nails and pre-drill the holes if you're fixing into old timber. Punch the nails just below the surface and fill the hole with builder's putty.

Step 11

Mark and cut the scribers. These pieces of wood are shaped in the same profile of the weatherboard, so they butt up to the external architrave of the door, fit around each weatherboard and butt into the top flashing and the door sill. Fill any gaps with No More Gaps and paint.

Step 12

Paint the doors with two coats of primer and three coats of top coat, using oil-based paint.

Step 13

Attach locks and clasps to the door to secure it.

Step 14

Gib, stop and paint the interior.

Step 15

Cut, paint and fit new architraves.