Roofs

[D.M. Procida]

This may turn out to be a stupid question, but I have nothing to prove...

I don't understand why it isn't possible to make roofs cheaply, using board materials instead of tiles or glass fibre. It's possible to make boats waterproof, with appropriate sealing materials and pain, so why not roofs, which have to deal with a lot less water?

It would be convenient and cheap to put large plywood boards on a roof, make sure that there's some kind of overlap or flexible seal where their edges meet, and finish them with thoroughly waterproof paint.

I'm assuming that I'm not a genius who has thought of something that has never occurred to anyone else, and there is a reason why this isn't done

- what is it?

Daniele

[Tim S]

D.M. Procida coughed up some electrons that declared:

Possibly the stronger exposure to wind, cold and rain and sunlight will make it harder to get a durable enough finish with paint; and the fact no-one will be bothered to repaint them often enough? Just a guess. Felted roofs are the nearest equivalent and even the best done don't have the life of a tiled roof.

Much the same could be said of boats, but I suspect boat owners are more fastidious about maintenance than many home owners.

Other views???

Cheers

Tim

[meow2222]

What you describe sounds like the precursor of roofing felt. The roof was boarded and painted with bitumen. To make it last longer it was then sprinkled with sand. Yes, it works, but felt is less likely to leak.

The Bradford stadium that burnt down in the 80s and was built before WW1 had a bitumen painted tarpaulin as a roof covering.

NT

[Dave Plowman (News)]

I'd not fancy having to paint a roof every other year. A well made slate etc roof can have a life of 100 years or so with little to no maintenance.

And the cost of replacing a roof tends to be mostly labour rather than materials - so I doubt a wood one would be that much cheaper.

[Cash]

They do, but they have a comparatively short life compared to the 'traditional' coverings - and glass fibre coverings on a close boarded roof are generally more expensive and time consuming to lay, particularly on a 'pitched' roof (there may be differing opinions on this BTW).

Again they do - but with the same results as above. As a matter of interest, some roofs are 'timber sheeted' with traditional coverings such as slate and tile and are called Close Boarded Roofs - and are very expensive.

A great deal of exposure to the sunlight and the UV rays tend to destroy the 'painted' coverings over a relatively short period of time (around 10 years or so).

When you consider that Welsh slate, Belgium slate and stone tiled roofs can have a life in excess of 100 years (cement slates are less than this) and a concrete or clay tiled one of around 30 - 100 years, all with a good, long lasting aesthetic appearance - then a 'painted' or felted roof really is a no-brainer both cost wise and aesthetically. Again, opinions will differ, but the test of time has proved which are best to use.

Cash

[Matty F]

The last two houses that I have seen built around here have a plywood roof covered in copper sheet or copper tiles. They should not need painting.

[Rod]

One of the things that really hit me on a visit to Latvia was the number of painted roofs. Mostly red. But I did not get to see what was under the paint - maybe galvanised panels? (I think I could see seams on some of them.) And many others had obvious corrugated sheets.

If the panels could be made full length (from ridge to gutter), it could make sense. Even better if the sheet edges could be non-flat (like tiles

- with some waviness or shaped edges) so that there isn't a simple overlap. But even then, one of the biggest problems is expansion and contraction - over the temperature range of a typical roof I'd guess that was pretty considerable.

[John]

we seem to be stuck in a methodology which requires all parts of a house to be handled by hand.

I recently saw a (temporary) structure for a supermarket which was undergoing development - it was build from foam filled aluminium panels about 20 feet by 10 feet - and 5 inches thick. Insulation would have been good.

[The Natural Philosopher]

And that is probably one reason its not standard practice. Fire.

[Tim Lamb]

You can easily get plastic coated, galvanised, rolled steel sheeting in a variety of colours and finishes. Pan tile effect, slate etc. Some are manufactured with a sandwich of insulating material to meet the building regs. Mostly targeted at industrial or agricultural use and they don't seem to have solved guttering related to domestic property issues.

There is just the teeny problem of satisfying town planning officers.

I was slightly surprised to find complete *villas* constructed of box section rolled steel sheet in Tobago but I guess planning rules are a bit less rigid there.

regards

>

[TheOldFellow]

I remember watching a (Norm Abrams) American program once where they built an entire house with stressed-skin panels. Each prefab wall and roof panel was plywood-skinned over a foam core edged with timber. They were bolted together, and down to the foundations. The panels were huge, so the constructors used a large mobile crane, but the basic structure only took a few hours to do.

The roof was pre-covered with felt shingles, IIRC.

I've used light stressed-skin panels in constructions and they are excellent in all respects. I would think a 12mm plywood skin over a

150mm core will easily carry a couple of guys jumping up and down - and you get 150mm of foam insulation thrown in.

R.

[Huge]

It is possible. Most American houses have roofs constructed this way. They last about 10 years.

[<me9]

One problem with copper is that they can be very noisy. Special felt is required under the copper to minimise it. Also theft possibilities are almost as bad as with lead.

[Dave Plowman (News)]

Not convenient or cheap, then?

[Dave Plowman (News)]

And I'll bet it leaked at the joins in short order. It's near impossible to cope with the expansion such panels suffer in the sun. A small leak in a warehouse isn't so important as in a house.

[John]

And many American homes have that superb benefit - A basement! Somewhere for the C/H Boiler - somewhere for hobbies and storage. I would love one. I think our dirty damp cellars of the Victorian era put us off cellars. They could work well with decent materials and design.

[george (dicegeorge)]

what's the difference between a cellar and a basement?

The cellar here has lime mortar walls so damp can seep in even when I've filled in the holes...

How can it be improved?

[Rod]

And I just visited our local Sainsbury store - which is a temporary structure. From inside it feels as if the roof is actually inflatable. But the walls are fairly obviously foam filled ali (or similar).

[damduck-egg]

Houses made from Cast Iron components were tried back in the 1920's. I expect some readers have visited the Black Country museum and seen the pair reassembled there. Outwardly they looked fairly conventional . Link here

wonder if any the others of the 500 mentioned survive. Bet they have caught a few people out over the years who naturally expected to drill into masonry. Also I seem to recall the original insulation was Asbestos based which could cause problems now if work which disturbs it is required. I cannot recollect what the roof material is ,Cast iron tiles would be a bit heavy so I suspect that it is conventional roofing material.

G.harman

[John]

I don't think you will fix it - but for a new build it should be possible to properly 'tank' it and have proper ventilation (for the boiler). Perhaps having it only three quarters below ground also helps.