Re-roofing a shed/workshop

[David Day]

Hi,

Ive just bought my first house and the workshop needs re-roofing, as its got a terrible leak causing it to smell badly inside. Ive measured the roof thats currently on there, and its 5.00m long by 3.35m wide, its pitched in the centre (2.50m either side), but only has a small angle on it. I need to re-roof it as cheap as possible, so decided to do it myself, saying that ive never done it before, but it looks reasonably straight forward. Any idea where to source the materials from? Screwfix, travis perkins or would a local wood merchant be cheaper? Also what type of felt etc would be best to use, bearing in mind that I need it to be cheap, but also last a while. Are there any guides around to show me the best way to re-roof? Are traditional nailed on felt better than pre-adessive? Will I need underlay? Its going to be used as a shed for storing stuff and the Occassional bit of work in there, but mainly it will have my home multi-gym in there and be used most days all year round.

I already plan to replace the wood under the felt, as im sure it wil need replacing.

I know there are alot of questions in there, and im probably not too clear, but i basically want to make an ok job of re-roofing my workshop/shed for as cheap as possible. Please help me.

Thanks,

Dave the (poor) fireman

[Andy Hall]

It's certainly worth investing in decent felt if you plan to stay in the place for a while because you will easily save the difference in longevity of the felt and the wood or sheet material below.

When I did this job on one shed I used a heavyweight felt together with a roofing sealer designed for cold fixing of felt. This did not need to be applied over the whole area, just a band either side of the joins. Starting at the bottom, the first row was laid and a fold formed underneath the eaves to prevent water from running over the felt and down the walls or more importantly the bottom edge of the wood. I should add that all timbers were treated with a good quality solvent based wood preservative before starting. Successive rows were then added with each overlapping the one below. On an apex roof, there is typically a small piece covering the top and overlapping on both sides.

Using this method, the shed is still completely water tight and timbers in good condition with no maintenance to the roof 15 years later.

The other aspect that you may want to consider is to insulate the walls and roof inside. Otherwise you will spend a lot heating it. At a rough guess, in the depth of winter you would need at least two 3kW fan heaters running full blast to just take the chill off the air, never mind achieving room temperature.

The good solution for this is to use Celotex sheet - it's good but relatively expensive, although you can get seconds. You would reduce the heat requirement to perhaps a quarter of that without insulation - all of these are round numbers. Alternatively, you can use glass fibre matting or styrofoam - less effective but less expensive as well.

[Staffbull]

Hi, roofed my sheds 5X5m and 2X3.5m with pond liner !! butyl 1mm stuff uv stable and still fine after 5 years. one pice so no leaky joins ruber glue from screwfix to the boards and Roberts your mothers brtoher!! =A3200 for the 5x5 if its designed to hold a couple of thousand litres in it'll keep showers out :-)

[meow2222]

Cheap felt is a false economy because the felt cost is not a large part of the job. But if you must, it does work, just doesnt last that well.

Last time I looked the nonadhesive felts were much cheaper than self adhesive. You need 2 layers minimum. If money is extremely tight its poss to use chipboard instead of something more suitable, but the first leak and it'll go so again its not the best choice. Soaking oil into the chip may help it.

Cheapest effective wood preservative is 50/50 engine oil and paraffin (or diesel or white spirit). Used oil's cheaper than new.

Cheapest insulation is a cardboard cavity. Just take cardboard boxes and cut them down to 2" high, then stick on the wall. One 2" cavity formed. Thin boxes can also be used, eg biscuit or dry catfood boxes.

Stepping outside of the box a bit here, our of curiosity anyone know what itd cost to cover a roof with cloth and tar it? Sheet cloth can be had from jumbles for next to nothing.

Are you sure you cant patch the roof for now, until more money is available?

NT

[David Day]

Im happy to do a decent job. Ive done the rounds of the local merchants and it looks like Jackson's are the best for materials. Its already boarded on the inside, but a few panels will need replacign, but ill do that at a later date, the roof is the main importance before it gets raining everyday. Anyway, here's what Jacksons have:

osb3 2440x1220x18 x6 £14.64 Rube U/S Zylex 1F Roof Felt 15m 561500 x2 £10.36 Rube Top-Sheet Slate 10m 35kg 560600 x2 £19.55 Aqaumac Feltfix Felt Adhesive 5l x2 £9.43 Nalex Clout nail ELH Galv 13mm 500g pack x2 £2.83

Does this sound like it will be ok, or is the underlay just coz the salesman wanted to sell it? Also, is the felt decent or not. Its £19.55 + vat, but that doesnt mean much to me. I can afford £200 which is what it comes to, but dont know if I'd be best going elsewhere.

[dennis]

Have you looked at plastic? Its as cheap as that and lasts for years. It does depend on where it is as to what it looks like. My shed roof is done in clear sheets and I grow plants in it in the spring. It gets dirty in the summer so it doesn't get hot.

If its a very shallow angle (my car port has a drop of

[meow2222]

All sounds good to me, though I dont know the Rube product, it sounds right ballpark costwise, and chipped slate finish looks good.

BTW I'd forget about trying to separate reboarding and refelting, either do both or neither. One thing that can knacker felt prematurely is putting it over gaps, if there are cracks between boards I'd fill them very briefly with something, pretty much anything will do. Then you should be good to go for many years.

NT

[David Day]

All sounds good to me, though I dont know the Rube product, it sounds right ballpark costwise, and chipped slate finish looks good.

BTW I'd forget about trying to separate reboarding and refelting, either do both or neither. One thing that can knacker felt prematurely is putting it over gaps, if there are cracks between boards I'd fill them very briefly with something, pretty much anything will do. Then you should be good to go for many years.

NT

Thanks for that. Re-assurance is invaluable. Il be replacing the whole roof boarding, as its soggy, and sagging. Ill make sure that there is no gaps. Thanks for the heads up.

Dave

[John Rumm]

Looks about right...

It is worth getting a hessian reinforced nail prep layer if they have it. It tends to be harder to pull away, and is less likely to break at joints in the boards. If you also make sure the new boards are well screwed at the edges so that can not move relative to each other, you will also prevent damaging the underside of the felt.

So ideally, nail the first one down well with the clout nails - random pattern of nails, the glue undercoat and top coat to that. Nice drip at the edge and job done.

[keith_765]

x6 ?14.64

Rubberoid U/S Zylex 1F Roof Felt 15m This BS747 1F is not suitable for flat roofs. Its an underlay for slated or a tiled roof. You would be better using a mineral felt.