Flat roof

Flat Roof Fitting

Points to note if you're getting a flat roof fixed

Firstly; you should not attempt to lay roof felt in wet or cold weather, because it will make it much harder (if not impossible). You will want to unroll your roofing felt around half an hour before you begin work, to give the material time to adjust to being flat, and it is best to unroll it on the roof itself. The underlay felt has to be fixed down first, so remember to start by unrolling that. You will need to lay the underlay at right angles following the fall of the roof.

house on river


Use a sharp craft or Stanley knife to cut the underlay felt to size. Beginning at the centre of the sheet you will need to nail the felt onto the decking using 20mm galvanised clout nails, spacing them 150mm apart. Work along one edge of the material toward the edge of the roof smoothing the felt as you work. Repeat this from the middle of the material in the other direction, toward the opposite edge of the roof, until one side of the underlay is attached. Do not fix the other side down yet.


Once the first layer of underlay is in place, you will need to apply the second layer. This will need to be fixed using adhesive and you should cut the first sheet to half size before you begin, in order to avoid placing joins directly on top of one another. First roll out the felt and cut it to size, making sure the alignment is correct, then roll it back up again (from the edge of the roof to the middle). Apply the adhesive on top of the first layer of roofing according to the manufacturers' instructions.

Gutter drips

Carefully roll out the second layer over the first, ensuring that no air is trapped between the two sheets and that you stick down the edges firmly. Once the first half is fully secure, you will need to roll up the other half and repeat the process. Do the same with the rest of the sheets until the roof is fully covered, overlapping at the joins by at least 50mm. Once the underlay is finished you need to fit the gutter drips before you lay the top sheet (which involves the same process of adhesive and fit that the second layer of underlay required).


If you aren't comfortable undertaking DIY jobs, you should always seek professional assistance to help you. This is not intended as an instructional guide, as every roof is different and may require different levels of attention. Flat roof home insurance is harder to get than insurance with regular roofing, as it is perceived as being at higher risk. Flat roof house insurance cover might be harder to come by, but because of the added risk it is vital that you get protection. With homeprotect you can get a competitive online quote for flat roof insurance, regardless of what type of flat roof you have.

Flat Roof Maintenance

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