Lowest angle for building a tiled pitch roof?

paddy147

Hi,just wondering whats the lowest angle you can go when building a pitched roof with roof tiles and velux windows?

Its for a kitchen extension.Roof would be comming down from window sill of the upstairs bedroom window at back of house.

Thanks.:)

muffler

Generally it's 17.5 but you need to factor in exposure etc. Search the tile manufacturer's web site for more detailed advice.

paddy147

muffler wrote: »

Generally it's 17.5 but you need to factor in exposure etc. Search the tile manufacturer's web site for more detailed advice.

Thats for velux windows installed aswell??

I read somewhere a few months back that they have to be at a certain angle or they will leak and not work.

is that ture?

Poor Uncle Tom

Taken from their brochure...

On the centre-pivot, a near flush fitting is achieved using the SD5N1 variant for flat roofing material up to 8mm and roof pitches from 35°-90°. The SD5P1 is specifically for plain tiles in roof pitches of between 25°-90°. Whereas the SD5W1 variant is for flat or profiled roofing material of up to 120mm and roof pitches from 15°-90°.

paddy147

Thanks for that.:)

paddy147

The span of the area to be roofed is just a shade over 9 feet wide (109 inches)

The height up is just over 3 feet (37 inches).

Can anyone please tell me what the angle of that is then?

Or how do you calculate the angle?

Thanks.:)

owenmul

given that the opposite length is 37 inches and the adajcent is 109 inches then:

tan of the angle = opposite/adajcent therefore

angle=tan^-1(37/109) --> then the angle is 18.75 degrees.:)

paddy147

owenmul wrote: »

given that the opposite length is 37 inches and the adajcent is 109 inches then:

tan of the angle = opposite/adajcent therefore

angle=tan^-1(37/109) --> then the angle is 18.75 degrees.:)

Thankyou for that.

is that ok for a roof with roof tiles or slates and 2 large velux windows??/

Heres a pic of what my house extension will hopefully look like.The red line is the roof in question.

muffler

paddy147 wrote: »

is that ok for a roof with roof tiles or slates and 2 large velux windows??/

Ah c'mon now paddy. Dont be moving the goalposts here. You asked about a "tiled" roof and now you are throwing in the "slate" word.

Please be clear in what you are asking as slates are a completely different animal.

Poor Uncle Tom

Too low a pitch for slate.

owenmul

Poor Uncle Tom wrote: »

Too low a pitch for slate.

why's that tom?

Poor Uncle Tom

The relevant part of BS 5534 is

5.3.4.3 Roof pitch
The recommended roof pitch and minimum head-laps for double-lap, natural, fibre-cement and other artificial slates, nail-fixed or hook-fixed, should be obtained from Table 4 and Table 5. The roof pitch should be not less than 20°.

Of course if you want a slate finish you can cover a lower pitch in a water proof substance (say torch on) and slate over it, that way you are not depending on the slate to keep the rain out.

One of the bigger manufacturers are recommending a minimum pitch for slate of 25 degrees, upped from 22 degrees 2 or 3 years ago.

owenmul

Poor Uncle Tom wrote: »

The relevant part of BS 5534 is

5.3.4.3 Roof pitch
The recommended roof pitch and minimum head-laps for double-lap, natural, fibre-cement and other artificial slates, nail-fixed or hook-fixed, should be obtained from Table 4 and Table 5. The roof pitch should be not less than 20°.

Of course if you want a slate finish you can cover a lower pitch in a water proof substance (say torch on) and slate over it, that way you are not depending on the slate to keep the rain out.

One of the bigger manufacturers are recommending a minimum pitch for slate of 25 degrees, upped from 22 degrees 2 or 3 years ago.

thanks, didnt know that

paddy147

muffler wrote: »

Ah c'mon now paddy. Dont be moving the goalposts here. You asked about a "tiled" roof and now you are throwing in the "slate" word.

Please be clear in what you are asking as slates are a completely different animal.

Sorry............roof tiles.:)

The kitchen roof is to look the same as or as close to as the existing house roof.So roof tiles it is.

Sorry for the mix up.Im not a builder,as you may gather by now..

Pic of existing roof.

cork2

as much as i hate them why not go for a flat roof? you are tempting faith in my opinion tiling a roof at 18 degrees. in the last 4 months ive fixed sooo many leaks and its regularly down to gales blowing rain water back up under the tiles.

gman2k

Poor Uncle Tom wrote: »

Too low a pitch for slate.

Not necessarily.
If you speak directly with a quality roof slate manufacturer, they will spec a construction build up to go much lower than what is generally considered to be the minimum.
Battens on counter battens, increased lap on membranes, increased headlaps on slates etc can all be utilised.
You can even construct a torch on roof under a slated roof for ultra low angles.
I agree that Veluxs can be a spanner in the works however.

DaireSVK

There is a French product called a HP10 which is a flat clay tile which is certified to a pitch of 17.5* Its made by a french company called Imery's. Might be worth a look. It is available in the Irish market. I used it on my own house last year. Looks a lot better then a concrete tile also it smooth so it doesnt encourage moss growth.

DOCARCH

Centurion roof tiles from Roadstone can go down to 12.5 degress!

paddy147

All sorted now.Thanks.

YouWantWhat

paddy147 wrote: »

Hi,just wondering whats the lowest angle you can go when building a pitched roof with roof tiles and velux windows?

Its for a kitchen extension.Roof would be comming down from window sill of the upstairs bedroom window at back of house.

Thanks.:)

You can go as low as you want with the slates or tiles. The minimum recommended pitch on the manufacturers info is lowest pitch at which water will not be blown or creep up under the slate or tile. The thing to do is to design the elements under the slates to accept water if it gets in. For instance, use two layers of a good quality roofing felt, laid at right angles to each other, and make sure all the joints are well lapped and taped.

muffler

YouWantWhat wrote: »

You can go as low as you want with the slates or tiles. The minimum recommended pitch on the manufacturers info is lowest pitch at which water will not be blown or creep up under the slate or tile. The thing to do is to design the elements under the slates to accept water if it gets in. For instance, use two layers of a good quality roofing felt, laid at right angles to each other, and make sure all the joints are well lapped and taped.

That is terrible advice to offer anyone.

If you have a specific design of your own then you should contact the NSAI, get your Agrement Cert and then post back and tell us how good it is.

gabbo is coming

Poor Uncle Tom wrote: »

Taken from their brochure...

On the centre-pivot, a near flush fitting is achieved using the SD5N1 variant for flat roofing material up to 8mm and roof pitches from 35°-90°. The SD5P1 is specifically for plain tiles in roof pitches of between 25°-90°. Whereas the SD5W1 variant is for flat or profiled roofing material of up to 120mm and roof pitches from 15°-90°.

Is this for conservation windows - cause normal centre pivot windows are all 15-90 degrees

Poor Uncle Tom

Even though the roof may be flat the window is risen up higher on the top side than the lower side to give it a sloping appearence between 15 and 90 degrees and thus centre pivot is used.

gabbo is coming

Poor Uncle Tom wrote: »

Even though the roof may be flat the window is risen up higher on the top side than the lower side to give it a sloping appearence between 15 and 90 degrees and thus centre pivot is used.

I'm a bit thick - does this mean that once the roof itself, is of a minimum pitch of 15 degrees - it will take a "normal" centre-point velux without fear of leaking?

Poor Uncle Tom

That's my reading of it too, you can always check with the company itself.

roofhelper

hello everyone,
just looking through the comments, roadstone do a tile called the centurion, which goes down to 12.5 degrees and in some cases 10 degrees, stay away from flat roofs, ok for first few years but soon come back to cause problems!!

bunglemark2

Interesting and very relevant thread this in my case..

I have a very low pitch sunroom attached to my house. When I bought the house, there was a problem with a sagging roof, which I had rebuilt, and reused two Velux windows from the previous roof. I dropped the pitch a bit, but not enough (I reckon) so the pitch now is still a relatively shallow 5-10 degrees.
The roof is a tiled roof in keeping with the same tile on the main roof of the house.
The reason I couldn't make it a steeper pitch is because the room extends quite a bit from the back of the house into the garden, and I didn't want a complete rebuild of the entire sunroom.
Anyway, now I have a small leak (ANY leak is a big problem, IMO) in the bottom corner of one of the two windows. Any time there's a prolonged downpour and/or wind, water comes in one corner in a steady enough drip...not a downpour, but enough to make me stick a bucket on the wooden floor inside.
My question is, should I invest in a brand new flashing kit (Velux), bearing in mind that the one up there has been installed (originally), taken down (when I had the roof taken off), put back in place....and is now possibly not working correctly ? Or would that be a waste of time if the pitch is too low anyway ?
Is there another flashing kit suitable for lower pitches ? Or can I double up or treble up to try to keep the rain from coming in ?

Any help greatly appreciated 'cos I want to get this fixed before the winter comes and I'm really p***ed off about this.
Thanks folks.

DOCARCH

Velux roof windows (and the flashings) are designed for a minimum roof pitch of 15 degrees, so replacing the flashings is unlikely to help.

Reckon you need to get a builder/somebody to do a 'bodge' on it, probably with loads of silicon?

bunglemark2

That's what I'm trying to avoid mate, a botch job.
I know about the 15 degree pitch (been looking all night for a solution from Velux themselves for details of how to waterproof a velux window or rooflight on a flat roof but can't find one) but also wondering if there's a way of overlapping the tyvex or lengthening the tile overlap or anything to try and keep the water out.
I know there's a way to raise the height of the window at the back (top) and make the window sit proud of the roof, but I think that would stick out like a sore thumb. And the problem is only with one of the windows so maybe it's the flashing on just one of them ? Or maybe I'm just lucky that the other one isn't leaking ?

Poor Uncle Tom

Your problems, as I see them from what you say:
1. Re-Used flashing components,
2. Roof windows at a lower than recommended roof pitch for the flashings,
3. Roof pitch itself is lower than recommended.

Possible solutions:
1. Provide upstands for the roof windows and use the normal flashings,
2. Remove the roof windows altogether, or at least the leaky one,
3. Remove the tile and re-dress the roof in a singular skin flat roof material, on the premise that if rain water can't get under the roof skin it won't need to be directed out.
4. As per point 3 and re-tile over for aesthetic purposes only.

YouWantWhat

There are two barriers to the water ingress, the flashing around the rooflight and the roofing felt. Both are failing. I would say you need to strip the flashing around the rooflight and examine/repair any defects in it. Similarly for the dressing of the roofing felt under the flashing. If the roofing felt is not dressed correctly around the rooflight, water getting past the flashing will find its way into the building. You may need to add additional roof felt, and make sure it laps well up behind the rooflight flashing, test it, before fitting the flashing.

bunglemark2

Poor Uncle Tom wrote: »

Your problems, as I see them from what you say:
1. Re-Used flashing components,
2. Roof windows at a lower than recommended roof pitch for the flashings,
3. Roof pitch itself is lower than recommended.

Possible solutions:
1. Provide upstands for the roof windows and use the normal flashings,
2. Remove the roof windows altogether, or at least the leaky one,
3. Remove the tile and re-dress the roof in a singular skin flat roof material, on the premise that if rain water can't get under the roof skin it won't need to be directed out.
4. As per point 3 and re-tile over for aesthetic purposes only.

Thanks mate.

Just wondering as I said before if a brand new flashing kit "might" fix the problem ? Maybe a kit that hadn't been installed, removed, reinstalled etc. and simply put in new would keep the water out. I know the pitch is quite low so maybe not...
I want to keep the roof windows to bring some light into the room 'cos it's dark otherwise. What way does the upstand idea work, esp. with flashing - are there standard size upstands and flashing kits to go with it ?

Cheers

Poor Uncle Tom

It's the same type as this. I know this is on a flat roof but the principal is the same, talk to a carpenter they are not difficult to install.