Garden Shed roof – your questions and answers

My shed roof sags, what should I do?

If your shed roof is sagging, you need to first work out why it is sagging. This often occurs when there has been too much weight on the existing structure – this can be snow, ice, wind or the roofing materials on top of the wooden boards. Sometimes this wooden roof can bend, warp or simply rot.

The most common shed roofs which start to sag are shed roofs made with chipboard or OSB. Chipboard or OSB is really designed for interior use – however, it does not take much for the roof under the felt to get damp e.g. a small tear in the felt, capillary action in the roof (if the felt has not been installed correct or the pitch of the roof is small) or from condensation inside the shed due to a lack of ventilation.

To resolve the issue, you can bolster the shed roof up with additional framing. This should strengthen the roof stop if from sagging. Alternatively, you could take off the roof and purchase tongue and groove boards, nail these into place and re-felt the shed roof. It may be worth checking the felt anyway, as if there is a tear you may need to re-felt it, preferably with a polyester backed shed felt. For information on shed felt please view our shed felt buyers guide.

There’s water built up on my shed roof - what do I do?

If water has built up on the shed roof and does not fall off, this would suggest there is some sagging. This can be resolved as per the section above where additional framing support structures can lift it back into position.

The other cause of this is that the felt is rippled – in this case you may wish to consider re-felting the roof.

Can I get a tiled shed roof?

Yes, there are various types of tiled roofing covers, for example shingles. Some shingle companies require you to lay some felt under the shingles depending on the angle of the roof – and therefore please do check that before installing shingles.

What is the best shed roofing material?

We would recommend the best shed roofing felt which is fit for purpose and will last the longest, would be a polyester backed roofing felt. This is difficult to tear and has a longer lifespan.
Another great shed roofing material is EPDM which is a rubber membrane. This sometimes comes with a lifetime guarantee and will last longer than even the shed!

Is roofing felt necessary on a shed?

Yes, although roof boards will generally keep water out, water can get through some of the boards if there is a sustained amount of water landing on the roof. This is because timber can expand, contract, warp etc in different weather conditions and temperatures. If a knot hole falls out this can also allow water to get in. For this reason we would also advise a covering goes on top of the shed roof to keep the shed waterproof.

How much does it cost to re-felt a shed?

This would depend on the size of the shed. Roofing felt can be purchase from most local DIY stores and can range from around £15 to £60. Be also sure to purchase clout nails to nail the roofing felt down.