Garage interior boarding out

[Steve Senior]

Can you elaborate on this please? I'm very interested in skinflint options.

[Tricky Dicky]

The problem with any membrane and probably any paint on sealer is that the substrate will have to be clean and sound and after all the years this roof has been in place it will have a build up of detritus. Ask yourself the question do you really want to to be scraping odd muck from a asbestos roof. I would also be wary of clambering up such a roof as the asbestos/cement loses a lot of its strength over time. When we removed an asbestos roof from a 1975 concrete garage as we lifted sheets they simply split. I think I would remove the roof and replace with like for like Onduline. It would also give you the opportunity to remove the metal trusses and build a wooden framework which would make the process of insulating easier.

[Steve Senior]

The more I think about it the more I agree with you.

The problem in my head is trying to find a roofer that can do it for a reasonable cost. A bit of searching around yesterday and I came upon plenty of horror stories about thousands of pounds for a single garage roof replacement and some of them were bodge jobs.

[The Natural Philosopher]

Even at my age I would tackle that myself.

Probably using machine tiles that can handle a low pitch.

It's a case of screwing enough woodwork together battening out and then simply laying the tiles.

[Tim Lamb]

I did a 5m x 17m single pitch in steel insulated panels 2 years ago. (75mm foam sandwich) This included erecting the steel frame!

Fixings are by Tek screws directly into your existing frame. Capping can be ordered to suit your ridge angle.

The nice thing about steel roofing is that you can safely walk on it and it provides a suitable location for future solar panels.

[Tricky Dicky]

Another option is board the roof with OSB and use felt shingles. They are easy to lay and most come with a 15 - 20 year guarantee. Did this on a small shed worked out a little more expensive than sheet felt but looks and feels good.

Richard

[Theo]

Just use the pre-insulated steel+foam panels like I linked to you

Take down the asbestos (wear an FFP3 mask), double bag and take to the tip or whatever your local authority does with asbestos.

Cut foam panels to size, using a ladder lift them up, click them together into place over the existing frame. One pre-insulated roof done.

Took him an afternoon:

(the rest of the playlist is well worth watching too)

panelsell.com were quoting about £49 per square meter for an 80mm thick panel, let's say your garage roof is 3m x 5m including pitch, that would be £735.

If you bought bare 75mm PIR foam from Wickes (I wouldn't) it's £54 per sheet (2.88sqm) so that's £324. Plus you need all the fixings, expanding foam to seal it etc. So for an extra £400 you get a completely new roof that'll last for decades, rather than a crumbling roof which will only last for a short time before needing replacement.

Theo

[Steve Senior]

Thanks. I'm going to look into this.

Here's a view from the outside of the roof:

It does look like it's probably not worth patching / repairing to be fair.

Thanks, Steve

[alan_m]

Hard to tell with all that moss and algae. Spay with a 10:1 solution of water: BAC50 and leave it a couple of months for the weather to wash off the resultant dead moss and algae. Random ebay seller

- mailto : news {at} admac {dot} myzen {dot} co {dot} uk

[Theo]

If it were just about the roof, patching might get you a few more years. But if you're going to invest in insulating it, it seems a waste to insulate it and then have to replace the whole lot in a few years.

One thing that did occur to me is that extra insulation may be heavier than the light sheeting, and it's unclear how thick the steel is. It may be beneficial to add some additional timbers to take the weight. You can do the calculations to decide if it's necessary or just over engineer it cathedral style.

Another cheap and nasty solution would fibreglass loft roll held up against the roof by a network of strings. Not pretty or long lasting (it may cause the steel to rust by holding moisture) but if the roof is knackered and you don't care about the steel then you might get say 5 years and that allows you to put off replacement for a while if that's what you want.

Theo

[Animal]

OK. What free materials could you get? For timber framing, look for job lot wood disposals on the free sites For insulation, pir offcuts are aplenty, and people pay for skip space to get rid of them so they're likely to be happy for you to help yourself. You can fill awkward gaps with fibreglass, rockwool or whatever you can scrounge. For wall lining sheet, chucked out laminated chip furniture provides a fair bit of sheet. The huge downside is all this takes time to find, collect and extra time to fit. But if you're brassic it can get you there.

I wouldn't even consider using PIR insulation for a garage. Polystyrene is far cheaper and almost as good. And in most cases insulation isn't needed anyway.

You mention repairing the asbestos - what's wrong with it? If it's largely ok, it can often be fixed by wet brushing the junk off, and once dry paint on a coat of bitumen, add scrap bedsheet, more bitumen, sprinkle on sand et voila, you have a cheapskate felted roof. I've seen it done a couple of times and it lasted quite well. And repairs cost... nothing. The one thing I wouldn't do is walk on the asbestos. Ladders etc can keep you off it.

Similarly I see no reason to replace the steel frame if it's ok. If you must reove the asbestos for some reason, modern equivalents are a good option. Either hard fibre board or softer like onduline. Or if brassic pick up some junked roof sheet from an industrial refurb.

[Tim Lamb]

In message [e-mail], Steve Senior [e-mail] writes

Get a quote for cut to size insulated AS35 steel sheet from Steadmans of Carlisle. They do the rainwater drip undercut for you and will supply the folded ridge sheet together with 90deg. barge board lengths. You need pre-formed foam inserts to seal the ridge to the roof sheets. Suitable length Tek fixing screws for the laps and main fixings.

One point, these metal roofs tend to creak a bit with expansion from sunlight.

Don't attempt the cutting and insulation clean off yourself. It is not as easy as shown on that video!

[John Rumm]

It looks rather like they have bolted it with the bolts going in the valleys of the corrugations rather than the peaks. That means that water can settle next to the bolt head, and if the waterproofing washer / pad / cap etc starts to leak, then that is what you get. (fixings though the high bits means that even if the seal fails, there is no sitting water unless it is actually raining.

Going to be difficult to get a seal I would have thought. The uphill edge would be vulnerable.

Not tried the product - it might work.

Might be worth costing new Onduline panels[1] or similar -

A corrugated bituminous impregnated fibre board - they are somewhat flexible and quite easy to fit.

Or, bite the bullet, strip the roof and replace it with a OSB deck or similar, then apply torch one felt (easy DIY - you just need a big blow torch), or even shingles:

(very easy DIY - need a hammer!)

I first used them on a garden building, and was actually quite impressed with them:

(you could also make your roof a "warm deck" construction - which is simpler to implement well)

[John Rumm]

Yup that is a very low pitch as well - that also makes it harder to keep dry since water can probably track up the under side of the panels from the bottom edge. The general condition of it does not lend itself to treatment either since you would need to get it clean enough to even start. It is probably not safe to walk on either, which makes working on it harder.

You could pitch a whole new roof over that fairly easily and then roof it with whatever you like.

I think I would take off the whole roof, knock off the couple of courses of brick at the gable ends, and put a timber wall plate round the perimeter. Then cut yourself so matching rafters from 2x4", stick a pair up at one end with the birdsmouth joint nailed to the wall plate, do the same at the other, then put in a ridge beam. Add rafters on 600mm centres between em, and you would have a nice new structure to add whatever finish you want. Fill in the triangle at the gable ends with ply or OSB etc.

[Fredxx]

I'm not so sure. The second bolt in the pic does seem to go through the peak. And the nearest one may be a parallax issue?

[Theo]

Roughly how much does it cost from Steadmans, out of interest?

I can see it would make sense to have it pre-fabricated for you, but if you're trying to work to a budget how does it compare with the bare panels?

(given we're talking a small single garage here, not a barn)

Obviously a circular saw on the panels isn't going to be as good as a factory cut, but that depends on how much extra you'll pay for it.

Theo

[Tim Lamb]

Rather more than I remembered:-) I ordered 17 sheets of 80mm composite panel with a total length of 96.9m. The drip cut was included in the total price of £2719.07.

10x3m 306x350mm bend flashing in 0.7mm plastisol sheet at £7.77/m 300 off 115mm panel to purlin Tek fixing screws @ £0.137 ea. 300 off 22mm stitching screws @ £0.048 600 plastic caps @ £0.012

1. Rolls Butyl tape @ £2.78 ea.

17 ridge fillers @£1.30 ea

Haulage @ £195.00

Haulage might be a killer for you as they were determined to deliver using a 60ft. Artic. This was Spring 2021.

You need a special saw blade. Not cheap. ISTR we had a thread on this way back. The blade bite is limited by the tooth shape.

Talk to their sales. They are friendly:-) 016974 78277

[Animal]

no. Or pir insulation

Yup. Old asbestos can have cracks & design/construction defects that make sealant cartridges not effective

Overpriced & undereffective. In situ bitumen felt covers all construction errors as well as cracks, holes etc.

I wouldn't recommend torch-on for a diy beginner.

Part of diy is knowing when to not waste time & money.

[Theo]

I think they're 1m wide, so that's 97m2? That works out to be £27 per sqm - not bad.

Panelsell have 'seconds' in the £15-25 per sqm territory, but the 'firsts' are more expensive.

Panelsell have yards in Manchester, Essex and Gravesend. They don't say what the costs are, but if you're local presumably you can collect.

it?

That discussion was about reciprocating and jigsaws. I'd be tempted to try a circular saw with a metal cutting blade - can't see the foam getting much in the way - would probably want a saw large enough to go through the whole panel in one go. Panelsell say:

1. Cutting insulated panels Sometimes it is necessary to cut down insulated panels to get them to working length on site.. For this purpose, the panels must be placed on a firm base and cut with a plunge saw, jigsaw or circular saw. It is important to make sure that the cutting surface does not become too hot during cutting. This could lead to the galvanization, and thus the corrosion protection, burning. Please do not use angle grinders or disc grinders as sparks could damage the anti-corrosion coating. Theo

[John Rumm]

Occasional use is actually a reason to insulate better, with the insulation on the inside. It allows you to get it to a comfortable temperature quickly and cheaply.

My workshop (12x17', with 50mm PIR on all walls and under the roof), can be got up to a comfortable temp in about 10 to 20 mins with a couple of kw of heat. It also "feels" so much nicer in there even without the heating on. It is also fairly cheap to keep it above the dew point (wall mounted fan heater on a thermostat set to about 5 degrees) which is quite important if you are keeping metal stuff in there (like tools or gym equipment) that you don't want to rust.

Having seen the photo posted since, I think any in-situ remedy is going to be a non starter.

I would - having tried many ways, it is by far the quickest and easiest

- it also gives very good results if you use a decent undercoat and a cap sheet.

It is really just a case of layout the sheet, cut to length and roll up. Play the torch along the leading edge of the roll and the roof deck, and slowly kick it forward. Far easier than messing about spreading out cans of sticky gloop, or turning it into a Swiss cheese with nails!

Trying to "fix" the existing roof would likely fall into that category. Its is in a poor state, and very low pitch.