Long life shed roof
Do you like wasting your time crawling onto rickety shed roofs and fitting overpriced low quality roofing felt, only for it to degrade, leak and blow off a year or two later? Personally I can think of better things to do, If you can too, this page is for you.
Replace a shed roof
Here I’m going to show you the easiest way to fit a super long life new shed roof to a professional standard for the lowest cost possible. In fact for probably almost the same price as the absolute crap quality felt sold by DIY chains, you can fit something that could last over 30 Years.
How to fit shed felt
Fitting shed felt is very easy once the old felt is removed and the roof is clean of residual nails, splinters and bits of old felt. In these two videos I will show you how to strip off the old roof covering not only for standard nailed felt roofs but also those roofs stuck with adhesive, hot flame or bitumen. Then in part two we fit the new shed roof.
Although I give a brief nod to safety in both videos I cannot provide full health and safety advice and a method statement. Please use common sense, or use Google to fill in any blanks.
What is the cost of a new shed roof ?
Expect to pay in the region of £200 to felt a shed roof like the one seen in the video if you have to call in a roofer or handyman. Whilst the price to fit something as simple as a replacement shed roof may seem a little steep, keep in mind that time taken fitting shed felt is time a trained professional isn’t spending on other well paid work.
Materials required for a new shed roof
The real beauty of installing a professional quality roofing felt to a shed roof is the utter lack of specialist tools required, unlike other high performance roof coverings. A hammer, a craft knife (preferably with a hooked blade but not essential), an old 2″ brush and a flat pry bar as seen in my roofing tools section will help. Oh and some felt, nails and adhesive listed below. Not exactly a big list is it?
The basics – This really is the bare minimum required, and most people will already own some of these basic items. A flat pry bar or hacksaw blade may help to remove any wooden trims without damage, as seen in the video on stripping shed roofs.
Here is a printable Checklist / Shopping list for your shed roof project if you need it.
Best shed felt roof ever
For those who have never seen a professional grade roofing felt before, let me introduce you to mineral faced Torch on roofing felt. This is basically a final high performance flat roofing layer that is laid above the venting layer and underlay layer on modern flat roofs. Otherwise known as the ‘cap sheet’. Theses mineral coated Sun and UV resistant felts are designed and built for professional roofers giving insurance backed guarantees, often for 10 to 20 years. So yes, they’re going to be pretty good on a sloped shed roof.
Shed felt colour choices – As well as being available online, roofing felt can of course be bought from your local roofing supplies merchant. Simply ask for “3.5k green mineral Torch on” or “mineral cap sheet”, other colours and weights may be available and are explained below.
Do I need any other layers ?
A simple garden shed will not require any venting or underlay layers flat roofs require, and the Torch on cap sheet is usually sold in either 8 metre or 10 metre roll lengths, with the width being a standard 1 metre. This obviously this makes working out your surface area and felt coverage as easy as measuring your shed roof in metres, and then working out the square metreage required.
Shed felt colour and weight
Professional roofing felts not only come in different colours but different weights too, which is another way of saying thickness. Most suitable for a shed roof is 3.5k, 4k, or 4.5k, the weight goes up per square metre of coverage, so will the thickness. Normally for a shed roof I would use 3.5k on a small shed, and 4k on larger sheds. There are sometimes other colours available apart from the standard green and brown, you may also find a purple or grey too, although they can be more expensive and harder to find depending on stockist.
The phrase ‘Torch-on’ isn’t just the type of roofing felt, it points to the method of application. On flat roofs these felts are laid with a very large blowlamp or ‘Torch’, as this burns off the plastic backing and melts the bitumen simultaneously. This doesn’t stop you using it for a shed roof though, because a shed roof is pitched or sloped, not flat. And of course we can always glue the joins with adhesive for shallow pitches or windy locations.
A modern torch on cap sheet is very tough thanks to the layer of internal reinforcing that is typically Polyester but can also be Fibreglass, this also makes it very strong when nailed into. You may see the phrase SBS or APP also mentioned when buying torch on, don’t let this confuse you, either will be fine for shed roof purposes.
Nail length for shed roofing felt
Most commonly I tend to use 15mm galvanised Clout nails, these are long enough to pass through 4mm of high performance felt and not penetrate the 12 – 15mm shed roof timber underneath. Remember they still have to be long enough to penetrate 2 layers of felt on the overlapping joints, and get some purchase into the timber of the roof as well. Most small sheds like the one in the video can be completed with approximately 100 to 150 clout nails, which I believe is roughly a 200g bag.
Shed felt glue
The adhesive I use to glue down the roofing felt seen in the videos is standard felt adhesive available online and just about every large DIY chain for about £10 or less. Although the Torch on roofing felts used are designed to be applied with a roofers blow torch, you will find glue offers very good adhesion, and even though you can fit a shed roof without the use of felt glue if the roof isn’t too shallow or exposed to wind blowing rain back underneath the laps, for what it costs why skip it? 1 Litre will be more than adequate on most shed roofs for bonding overlaps.
If you live in a particularly exposed location for wind or your shed roof is of an unusual design or pitch, you could consider fully bonding the Torch on cap sheet to the surface of the wood with shed felt adhesive as well as using nails. One generous helping of adhesive rolled or brushed onto the mating surface of the shed roof timber before rolling or placing the felt into it, works very well.
Shed roof repair
If you have a small spit or hole in a shed roof it can also be repaired with the felt adhesive mentioned above. Simply cut a patch of green mineral felt 50mm (2″) larger in every direction than the repair requires. Ensure the mating surfaces is clean and dry, they apply adhesive to the damaged area, and the underside of the repair patch. Simply wait to the adhesive to flash dry as per instructions and nail to finish.
Felting a long shed roof
Sometimes when you replace a shed roof it’s extremely long or wide, or has a severe dip in the middle. This can make the standard horizontal application of felt tricky near the apex when large horizontal lengths of felt do not want to follow the curve of the roof. This can then start creating large unsightly sags of felt that are not touching the wood beneath.
The shed above has separate vertical sections of felt both front and back, then capped at the apex with smaller dedicated pieces. Another way would be to simply run the felt up and over in one piece.
Best shed roof alternatives
Is there something better than felt for a shed? Although as a professional roofer it’s not high on my list of preferred jobs, I’ve covered more shed roofs than I care to think about in a variety of materials like Fibreglass, EPDM rubber, PVC’s like TPO and of course Felt. But never DIY grade felt bought from the big DIY stores. Ever.
Although there can be merit in fitting the expensive materials listed above on occasion, they inflate the price substantially through material costs, labour and pure faff. Although I have fitted all of the above, for a price versus return ratio, and probably in environmental terms professional roofing felt is hard to beat.
- Best new flat roof – Modern flat roofs compared
- How to fibreglass a bay roof – Another small low level project?