Of course the wind can gust in different ways and there are many types of roof tiles and house heights differ .... but, as a rule of thumb, what average wind speed would make it more than likely a tile comes off a roof?
According to the Tile Roofing Institute, *properly attached* clay roof tiles can withstand wind speeds of up to 125mph. However, once the speed exceed 110mph the main danger to tile roofs is being broken by flying debris. That can have a cascade effect that can strip whole sections of roof.
Beaufort scale gives :-
Strong/severe gale 41?47 knots Slight structural damage (chimney pots and slates removed).
Full scale and background
The Met Office lost £4000 worth of wind measuring gear on the IOW that was supposed to be good for about 100 mph.
Must have been a big gust, which are the ones that tend to do the damage to tiles and fence panels.
Probably more damage done by short gusts of wind and/or the wind being directed around an obstruction (chimney etc.) and hitting a slate or tile from more than one direction at the same time.
Half past three or maybe 6' 2 1/4". B-)
Today has seen the third day this month over F8 (Gale - low 40's mph sustained) force winds. Only one gust over 60 mph today though. In over twenty years we have yet to lose a slate, they rattle a bit mind.
That's a measured wind speed, with the anemometer fairly low at about
10' above the ground. When we had scaffolding up the wind could be barely noticeable at ground level but get up to the chimenys and you needed to hold on... I dread to think what it's like up there when its 40+ mph sustained at ground level!That is an impossible question to answer as you say, too many variables involved. Brian
The other issue is pressure build up inside the building if a door is open then a roof tile can easily get blown outward. My loft has no lining under the tiles, so is prone to this sort of effect, sadly. However thus far they have only shifted and a quick repair done by a roofer, though they do tend to do the chin stroking and express the need for a new roof, but then they would say that!
Brian
Top o' Skiddaw, hear gust approaching, crouch/lay down and try to hold on (it's a heap of slate-like stones - nothing to grab). In the woods not too far down the wind was just a stiff breeze. There were trees down at various angles, some in the middle of standing trees. Now, if the wind at 3000'+ is too strong to stand, what the hell is it like up there when trees are being blown down a thousand feet lower? Had the same on Carantouhill, 3414' SW Ireland, but there were rocky outcrops to grab.
Tile roofs are typically twice as heavy as slate roofs, so are less likely to lift in strong winds.
Wouldn't llike to bet on that. Slates are effectively laid across three battens nailed to the middle one just below centre of the slate, resulting in a > 50% overlap. The top edge of the lowest slate clamped to the upper batten by the slate above and its nails. This slate is clmaping the next lower slate with it's nails. With this effective double fixing to the battens you can't lift the lower exposed edge of a slate.
Plain tiles are hung on the batten and nailed at the top, with the best part of a 50% overlap but it's still fairly easy to lift the lower edge of a tile and with the large mechanical advantge pull the nails out of the batten. That's always assuming every tile is nailed.
Interlocking or pantiles have little overlap but the side interlock means that a row has to lift more or less together along the bottom edge.
Windy. B-)
Great Dunn Fell (848 m, 2780') is 7 miles to the south of us and if it wasn't for a slight rise in the land between us would be line of sight. Yesterday the met office weather station on GDF a few recorded a few gusts over 90 mph with sustained speeds in the upper 70's mph. That's around 10 mph more than normal for bad weather on GDF but the winds from Dennis were very variable and the strong periods didn't last long, just an hour or two.
A bad storm here can have winds running at F8/F9 (40 to 50 mph sustained) for over 24 hours, the noise gets wearing and it's nice when it stops.
Ciara and Dennis have been rather wet but nothing to write home about as far as wind is concerned. We are more likely to have problems with snow on Monday/Tuesday, probably without any met office warnings...
Wind in east anglia has been quite high with some tree damage.
Lot of water but no floods this time. was worse before xmas
Many years ago, a friend told me that in a particularly severe gale, he saw 'waves' running across his tiled roof, Mexican wave style, as the tiles lifted together in the gusts. Didn't lose any though.
From experience, you can lift it enough to get a nail ripper under the edge.
In this part of the world, slates are traditionally 'wet laid' scantle slates, with a fillet of mortar under the lower edge.
125 mph seems improbably high as I'm sure I have heard of gales (at half that wind speed) removing roof tiles.
We've had forecase gusts of 65mph last week (Ciara) and everything stayed put.
But I do have interlocking double pantile style concrete tiles, plus the roof is nearly airtight due to foamed in insulation from top to wall plate.
It's the felt that's more likely to get it here. But that's 8 years or so old and in good nick.
Apparently trees are more likely to be uprooted when a gale is not in the same direction as the prevailing wind, as they put down more roots on that side.
As mentioned it's not the average speeds but the bursts and circumstances / location.
Our wheelie bin is knocked over as soon as the wind picks up but my
16' plastic canoe (that I can lift easier than the bin), upside down on two tall / plastic trestles in the garden hasn't moved (but a fence panel was blown out close to it)?We used to lose slates in some places on the edge of the roof (we are EOT) until a builder (also) tacked them down with silicone. If the wind repeatedly gets under slates lifting them a bit it can wear the nails out (or enlarge the hole in the slate) and allow them to break away.
Our roof was previously stripped, lined and re-slated (with most of the original slates), so the nails were new etc.
Cheers, T i m
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