How to build a porch wooden roof

Constructing a porch roof overhang above a door isn't difficult at all.

Sloped wooden roof
Sloped wooden roof

One of the most common inconveniences when it rains is that driving rain hits a door and doorstep, even up to the point that it sometimes penetrates the house.

The solution is to construct a small porch roof above the door which sticks out just enough to reduce the inconveniences caused by rain to a minimum. A porch roof provides, amongst other things, the advantage that it also protects a possible light above the door and reduces sunlight exposure.

With little cost and just a weekend's work you could build a simple, robust porch roof yourself, suitable for every kind of house from the most modern to the most rural.

The material which you'll use to cover the roof with should preferably go well together with that of the main roof. The roof overhang in this article will be covered with Italian clay tiles, but it is of course just as easy to cover it with ordinary tiles, bitumen shingles or whatever else you'd prefer. Also its slope should refer to that of the main roof in order to avoid a sense of unevenness when observing the whole from a distance.

The structure of such a roof is quite simple and doesn't require serious masonry work since the wooden roof will be anchored against the wall with strong expansion plugs.

The weight of the porch roof is distributed over the three main parts: the posts, the ties and the struts. The longer the posts, the better the structure will be able to carry heavier loads. For this particular project the posts have a length of 1,20m. Every post is fixed against the wall by means of strong bolts or screws and expansion plugs. In order for the screws to do their job properly you need a thick and solid wall of course.

Two purlins with a size of 6x12x180 cm support the slope. One of these purlins is inserted in a slot behind the posts and also screwed tightly against the wall. The other one is placed about 6cm before the outer end of the ties and fixed with strong wood screws.

The rafters (size 7x8x110 cm) are put across the purlins at a distance of 40cm from each others. As you can see on the drawing appropriate cuts have been made in the purlins in order to accommodate the rafters because otherwise they'd only support on the edge of those.

Boards or planks are then put on these rafters which will carry the roof covering. In order to protect these against the rain you could put some bitumen on them before laying the tiles. That way you'll be absolutely sure that no water can pour in.

Sloped wooden roof

Once the structure is made, you should varnish it properly before mounting it in order to protect the wood against humidity and insects.

For a small porch roof like this, placed above a door, it isn't necessary to provide a rain water gutter because it's main scope is only to protect the door against driving rain and hence not to let any water penetrate the house. Under normal circumstances only a small amount of rain should land on this roof because the largest part will already be covered by the main roof overhang and directed via the gutters towards the sewer.

Covering a roof begins at the outer end (the furthest away from the wall). If the roof is not too slanted it isn't necessary to fix the tiles with nails to prevent them from sliding off; simply putting them one over the other will be sufficient to keep them in place.

Before putting the last row of tiles you seal the junction between the last collection tiles and the wall with a thick cement mortar and repeat the same process after having laid the last covering tiles; this will avoid any water infiltration at a critical point, being the space between the roof and the wall.

DIY Editor
Do-it-yourself enthusiast. I started with the renovation of my flat and then I changhed this passion into my job.