Cheapest vs best garage roof

greensalad

I am looking to get my garage roof replaced. It is an original corrugated asbestos roof, it’s crumbling at the back, leaking, and the roof timbers have started to rot. 

It’s a single garage attached to my neighbours garage (both are completely separate from our houses, so this is one detached block of two garages). My neighbours have expressed an interest in getting theirs replaced too, so I planned to get quotes for just us and also the double replacement. 

I am wondering what is the cheapest vs what’s the best. I don’t want to go for something cheap but crap.

I’ve seen some corrugated steel types that you then have a little frontage of tiles. Looks nice but I’m sure it’s expensive.

On the other hand I’m going to guess that a standard felt roof is cheapest of all and I don’t think it’ll look out of place. We just had the felt replaced on a 50 year old roof that was probably a little bigger than the double garage and it was around £3000, but no timbers had to be swapped.

Any opinions? I really need to get this done as at present I’m having to only store select items because the whole garage is too damp from the leak. 

ThisIsWeird

Although felt roofs can, indeed, be very long lasting, I always feel they have the whiff of looking 'cheap' and 'temp' - with an often-unfair 'That'll need doing in 10 years" summation. Depending on (lack of) slope, they can also start to look tatty before their time due to moss and stuff. In reality, they should have an easy 20+ year lifespan with no issues.

My preference would be to go for the metal sheeting that you mention, in square 'box' profile. Depending on garage depth, these might be doable in single sheets, is a very straightforward task to fit (ideal DIY project, for example), comes in a range of colours, doesn't require the roof to be sheeted first (unlike felt, GRP and EPDM) but only for the rotten joists to be replaced. Large number of trims and fascias to make it all look very professional -  they 'look' like 'proper' roofs, and should be fit-and-forget.

Wouldn't your 'tiled frontage' require a change to the roof shape, with a raised ridge set back slightly from the front? Yes, I can see that costing a good bit more, but I think you'll find the actual metal roofing itself to be well priced, and labour costs should be lowish. Different thicknesses and finishes to compare, tho'.

ThisIsWeird

I'm personally very anti-EPDM since having to help patch up one on a local building when the evidence seemed to suggest it had been damaged by little more than a small branch used to retrieve a football; a wavy multi-scratch line leading from one edge, with a number of small perforations along it - and a large damp patch to the ceiling below... 

Again, tho', there's probably different grades and qualities, but I was always conscious that a stone chip on my sole could do the same. Not for me.

plumb1_2

Ya coated metal panels gets my vote.

ThisIsWeird

For your 'tiled frontage', there is always the option to mock one up after the proper roof has been done. A lightweight timber frame to provide the required slope, affixed carefully to/through the new roof, and some lightweight tile sheets attached - https://www.google.co.uk/search?q=lightweight+tile+roofing+sheets&source=lnms&tbm=isch&sa=X&ved=2ahUKEwjAoPPPgLD8AhXQTUEAHa1ZB08Q_AUoAnoECAEQBA&biw=1920&bih=899&dpr=1

I guess it'll come down to whether it can be viewed from the side, and how strong the winds are.

casper_gutman

Is the current roof flat or pitched? And how extensive is the damage to the existing roof timbers - if they're basically okay, then it will probably be sensible to choose a like-for-like replacement for the existing asbestos cement panels. If the whole structure is in need of replacement anyway then a wider range of options may become viable.

greensalad

casper_gutman said:

Is the current roof flat or pitched? And how extensive is the damage to the existing roof timbers - if they're basically okay, then it will probably be sensible to choose a like-for-like replacement for the existing asbestos cement panels. If the whole structure is in need of replacement anyway then a wider range of options may become viable.

It's flat but has a tilt. Higher at the front. 

The timbers have crumbled and rotted at the back where the most water ingress is, but at the front they are looking pretty ropey (at least that's what I was told) they seem to have had some insect damage at some point, but this is all original from 1965 so hardly surprising. 

I'm not too worried about the look of flat roof felt. A lot of other houses around the close have them, and it's a 1960s bungalow close with plain pitched rooves, blocky houses and concrete drivesways, so it's not like I'm putting a felt flat roof in the middle of some gorgeous Edwardian street or something like that! Plus we already have a large flat roof extension on the back. I'm happy to make the effort once a year of cleaning off the moss and leaf drop. 

I was thinking of getting some guttering added too and then having a water butt to water my front garden with. At present in the summer I have to run the hose through the bathroom window down the hall, or take can after can of water to do my front flower bed. 

ThisIsWeird

I'd get quotes for both options, then - felt and steel sheet. The felt option will be more labour-intensive, and also require ply or sterling board sheeting first.

I suspect there won't be too much in it, in which case I know which one I'd choose

Section62

greensalad said:

I was thinking of getting some guttering added too and then having a water butt to water my front garden with. At present in the summer I have to run the hose through the bathroom window down the hall, or take can after can of water to do my front flower bed. 

I would have said plastic coated steel anyday. I've not purchased any recently, but if you think felt would cost you and the neighbour in the region of £3k then I'd be surprised if steel was any more expensive (unless you go for something fancy).

However, if you want to harvest rainwater then plastic coated steel has the advantage of retaining less water than felt, also the runoff from steel is less likely to be contaminated with organic compounds of the kind that can leach out from felt.  Getting more (and cleaner) water would be an added bonus IMV.

greensalad

Good point on the rainwater collection on steel.

I think I will get some quotes for both. I'll get the guys who did my back roof back and get a quote from them as they were really good and efficient. 

Having just had a look around my close (there are only 14 houses) I've noted that everyone has something different. And we're also the pair with the ropiest looking garages! Some neighbours have the little tiled frontage and then either felt or steel behind. Several have a short brick upstand at the front and then felt behind. Some have full steel. But no one has pitched or anything, it's all sloped back. 

greensalad

Got a quote of £2,200 for the felt roof replacement with full new timbers.

Someone coming out for a steel roof quote next week. Their website says a guide price of "£950 to £2,500 with most in the range £1,100 to £1,400" for a double garage, and he said there would be savings doing the double with the neighbour but he's going to quote for each. I'm guessing the asbestos removal will up the bill, but if I could get it around the £1,500-£1,800 for the double garage I would be chuffed!