[?] How to repair a garage roof that is letting in the rain.

[David Chapman]

My son's 50 year old house has a detached garage with a roof made of sheets of overlapping corrugated mineral material (asbestos-like), sloping up from either side of the garage, and capped along its top by overlapping /\ shaped pieces of the same material. The roof is well supported inside the garage by means of a criss-cross structure made up of angle steel.

When it rains the garage roof leaks in some places - not a lot, but enough to wet anything stored in the wrong place below. When I went inside the garage and looked up I could see the sky through quite a few gaps where the /\-shaped capping pieces were supposed to be covering the two sloping side-pieces. The outside of the roof is covered by quite a lot of moss, much of it around the capping pieces so I'm wondering if its growth may be responsible for some of the problem.

I would like to ask three questions :

1. What is the most cost-effective way and best material to seal the gaps in order to deal with the water-ingress problem?

1. Are the roof sheets really likely to be a dangerous type of asbestos and, if so, what additional care should be taken handling/repairing it?

2. What is the best, and safest, way of actually getting onto the roof in order to clear the moss and actually effect the repairs?

Many TIA - Dave .

[Roger Wareham]

I had a similar problem with a moss-covered corrugated cement/fibre roof. Removing the moss cured it completely.

It seems that the moss was damming the water at the overlaps, causing it to rise under the overlapping sheet until it reached the top of the underlying sheet.

The roof in question was around 10 metres by 5 metres so removing the moss was tricky. I finally did it using a set of drain rods with the spiral bit first to loosen the moss then the disc bit to drag it off the roof. I taped a weight to the end of the rod to give it more purchase.

Stretching a couple of bare copper wires over the roof just below the ridge is supposed to prevent the moss regrowing, but it's too early to say whether this has worked yet.

HTH,

Roger.

[Nige Danton]

I had something similar with a garage flat roof a few years ago. It was covered in moss etc and letting water through in many places.

I used a short scaffold board on the roof to let me safely walk on it and used a stiff yard broom and a hose to clean the surfaces. Once it was clean and I could see it more clearly I replaced a few of the fasteners that had become badly corroded or loose and then applied a couple of coats of a bitumastic emulsion called"Ruffabrush". I bought a 25 litre tub very cheaply from a roofing supplier.

I had only planned it to be a short term fix - but just checking google - that was 7 odd years ago and it's still keeping the rain out.

-- Nige Danton

[Dave Liquorice]

At 50 years old asbestos cement panels are probably pretty much at the end of their life. I'd look to replacing them, maybe with a few translucent/parent ones to let in more light. What condition are the supporting angle irons, they might need looking at and maintaining if not replacing as well.

In this day and age *any* asbestos is considered dangerous. Hopefully you won't have to go to expense of total negative pressure enclosure of the entire structure for the removal of it but I wouldn't like to bet on it. It'll still have to be double bagged and disposed of properly though. Have a dig about on the web and see what you can find out before contacting an asbestos removal contractor (so you can spot any bullshit).

Very carefully on boards, the panels are likely to be very fragile.

[JoeJoe]

Asbestos is only dangerous is disturbed (i.e. grinding/drilling/cutting/breaking/etc). If you are careful when handling then you should be fine.

[meow2222]

really depends on the nature of the damage. I'd de-moss it and reassess first, then tell us exactly whats amiss if it still drips.

yes and no. At 50 yrs old they'll be white asbestos. The safety of free white asbestos is a matter of debate, however in your case its locked into cement sheets so not a serious issue. However there is a whole overpriced disposal industry that would love you to believe those sheets will kill you and your descendants for the next 1000 years, and that you must pay them 4 figures just to bin the sheets for you.

double bag it before disposal, and take to a tip that accepts asbestos. They will simply bury it. Break it if necessary but best not to saw/grind it.

Old asbestos roofs are considered fragile, so large loadspreading boards.

NT

[Huge]

Do it on a day when it's slashing down with rain, or if not, wet the whole thing down continuously with a hose, and wear a decent mask and disposable coverall. Dispose of the filter and coveralls with the boards.

And even that's likely overkill, but it's what I would do.