How to Build a Flat Roof

How to Build a Flat Roof How to Build a Flat Roof A flat roof is one of the most common types of storage shed. This type of roof shed is quite durable and if maintained properly would only require re-roofing every 10 to 20 years. Here is a step-by-step guide to help you build a flat roof.

Flat roofs are constructed with joists spanning the gap between two walls. Sheet timber or some other material is used as the covering. When timber is used, a further waterproof cover would also be required. The size of joists is calculated from the weight of the coverings and the span. Depending on the area you stay, take into account any possible extra load on the roof due to snow or other climatic interventions.
Before you start construction, ensure that you have the necessary building regulation approvals from the concerned authorities. Once you obtain the required permit, you can go ahead with building your shed roof.
Wall plates must be fitted first before you start with the joists. Wall plates facilitate easy fitting of the joists and provide a secure attachment. Fix 1’’x4’’ rough-cut timber to the top of the wall, using cement and fixings to ensure correct leveling. As far as possible, level the wall plates with each other as well as along the wall.
Now level the joists and fit them with 400mm spacing. Depending on the size of the joists, you can vary the spacing to 450mm or 600mm. Install noggins for every 2 metres of span. This will ensure that the gap between the joists remains consistent and will also prevent the joists from twisting.
Cut timber blocks lengthwise from corner to corner, creating very long triangles. These are called firings. They start at full thickness of the block and taper down completely. A firing should be fitted to each joist for lifting one side of the roof and creating a fall. The fall created depends on the thickness of the firing in relation to its length. You can purchase firings from any timber shop. If you are doing a cold roof system, it is advisable to put the insulation in at this stage.
For a cold roof construction, 50mm airspace is required over the insulation to provide ventilation. The minimum depth of the joist is generally taken as 175mm.
Clean the plywood of any accumulated debris. Now fit the decking boards along with the facia boards. A board should lie half way on the joist where it meets another board. If necessary, cut the board to ensure this happens. The boards should be of an exterior quality like plywood. If you are using the warm roof method of insulation, then install it at this stage.

Paint the entire roof with a tar based solution to ensure maximum longevity of your storage shed. Inspect the shed’s roof twice a year or when there is a bad storm. Examine the seams in the roof for any gaps and fix with roof cement where necessary. Also, ensure that there is no water build-up as it will make your roof heavy and cause it to collapse.