ROOFING EAVES DETAIL

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rhrwilliams
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ROOFING EAVES DETAIL

Postby rhrwilliams » Fri Sep 29, 2017 3:24 pm

I am re-roofing my house. Well to be technical roofers are doing that bit and I am doing the carpentry.

The roof is going to be insulated between the rafters (as there is a loft room and no insulation currently) and so the roof is to be counter battoned to provide an air gap between the felt and tiles.

Im struggling with the eaves detail on the front and sides due to the counter baton and was wondering if someone could offer me some wisdom.

Before the counter baton went on, there was no felt, and just a fillet / wedge / sprocket (whatever the name for it is) which the tiles laid over. Ive machined up a new one as per pics.

Now the Counter baton is on - does the wedge go on top of the counter baton ? If so you will have a weird gap that won't look very good.
Or do you make a bigger sprocket / wedge to hide the counter baton behind it
Does the felt go over the sprocket ?

If there is a standard way of dealing with this I would be all ears

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furynaturre
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Re: ROOFING EAVES DETAIL

Postby furynaturre » Fri Sep 29, 2017 4:09 pm

Hi There,

Assuming it's open eaves, rather than the tilting fillet you have currently running perpendicular to the rafters, you'd be better off cutting a proper sprocket for each individual rafter.

You don't say what type of tile you are using, (if it's slates be very cautious about the shape speak to your tiler as slating is not forgiving!) The sprocket is usually used to provide appropriate 'kick' on the last tiles whilst also altering the depth of the front of the rafter foot to provide adequate fixing for the fascia once the seat cut (at the sofit line) is made, usually only needed on roofs above about 40 degrees.

Not sure if I have helped or confused.


James

rhrwilliams
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Re: ROOFING EAVES DETAIL

Postby rhrwilliams » Fri Sep 29, 2017 4:29 pm

Thanks James.

The front (in the pictures) is closed off by a a soffit board fixed to the underside of the rafter feet. The remainder of the house is open eaves.

The tiles are peg tiles.

The fillet I have machined was there before and I just made a like for like one.

I think you might be right about the sprockets of the rear open eaves bit.

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Re: ROOFING EAVES DETAIL

Postby Meccarroll » Sun Oct 01, 2017 7:20 am

Sound like you have a bit of a mix going on front and back: One side open eaves rafters the other closed by a soffit. It sounds like someone has simply altered the original design slightly over time.

The splayed timber at the bottom (Eves) is simply there to support the end of the tiles, otherwise they would just fall through between the rafters.
A Facia board would do the same job in supporting the last row of tiles between the rafters.

Looking at the detail that you have now it would be simple to replace the splayed timber with a Facia board, that way you can make it as tall as necessary to hide the extra depth of the counter battens.

The detail I would consider would be:

Sprockets cut to the the height of new Facia and fixed on each rafter foot so the facia has a fixing, Soffit underneath which may need a batten at the wall side for fixing to and ply fixed on top of the sprockets along the length of the eaves which leads from the top of the Facia to the back of the first tile, the ply adds support to the under-felt at the eaves.

I normally speak to the tilers (main tiler as most are helpers) about the detail so it works both for them and myself.

There are a lot of variations that can be adopted to solve the same situation, it's just a matter of adopting the one that best suites the materials at hand and the tilers requirements.

Mark

Need any clarification just ask.

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Re: ROOFING EAVES DETAIL

Postby rhrwilliams » Sun Oct 01, 2017 7:17 pm

Mark,

thanks for the reply. (I don't know how to not have the pic I've attached be the correct way up - if you click it - its correct way up)

Yes you are 100% correct. Its a Georgian house with Oak rafters. The front roof was lifted (or straightened out) slightly in the Victorian period when the house was tarted up. Thats presumable when the open eaves went to closed eaves on the front.

What you have suggested is what Jon R suggested to me also so seems like a good idea ! Ive made a mock up today of what I think is suggested by both you and Jon.

image1.JPG


What I have not looked at though until today properly (from doing mock up) is all the other things that won't be correct if I raise the roof. The gable ends of the front roof will have to be raised and I will need another brick course. Its already been packed up for the Victorian modifications. The dormer window cill will have to be raised or altered as it will not have sufficient gap.

I think I will take the sensible advice of talking to the roofer before trying to work it all out myself tomorrow and se what he thinks. I think I may not counter baton though and go back with the original detail. Its worked for 300 years ;)

Old Houses - never simple.

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Re: ROOFING EAVES DETAIL

Postby Meccarroll » Tue Oct 03, 2017 8:30 pm

Try looking into some of the newer breathable roof coverings they may prove to be just what you need for this operation.

The last chunk of wood that is on the same plane as the battens and next to the facia is not needed as the facia supports the end of the tile. It's common practice to run 6-10mm ply from the facia to the edge of the first tile to support the felt at the eaves. A lot of dampness starts at the eaves because after a few years the felt begins to sag between the rafters and if water does get in it collects on the sagging felt and eventually rots the ends of the rafters by installing the ply at the eaves it prevents the felt from sagging and collecting water.

Mark

Ps The detail is about right but I would allow the tile to project at least 2.5 inches over the facia and maybe give it a slight kick up at the end by making the facia slightly deeper but I would still check this detail with the roofer first.

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Re: ROOFING EAVES DETAIL

Postby woodsmith » Wed Oct 04, 2017 8:51 am

Looks like this roof doesn't have fascia boards so will need a tile support batten. You will find that the bottom batten needs to be thicker than the rest of the roofing laths. If you Google clay tile eaves detail and look at images you will find lots of examples, although most show a fascia board you should get a better idea of what you need to do.

You can buy a specific felt support tray(screwfix sell them) to use at the eaves.

As Mark has said you need to project the tile further over the gutter.

The gutter looks far too small and shallow to take the water off the roof, it could be just camera angle but it looks like shed guttering.

I can't see from the picture so I don't know if you have one but the first tile at the eaves is a specific approx 2/3 length tile (you use the same short tile at the ridge). Some roofers just cut a standard tile down but this is a bodge at best. As you can't see them at the eaves (as they are hidden under the first full tiles) you can get new tiles for this with nailing holes and fix every tile down.
Keith

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Re: ROOFING EAVES DETAIL

Postby rhrwilliams » Wed Oct 04, 2017 8:55 am

Mark / Keith thanks for reply.

I had a chat with the roofers yesterday and a plan has been formulated.

Its a breather membrane. The first tile is a full tile nailed on its side , then the first tile goes over the top. Its like this on the house and all the out buildings.

I got a timber fillet wedge made up in doug fir so should last a while !

Its standard sized guttering which I am replacing with cast iron. perhaps a deeper flow one would be better. Porch has a lead roof and I'm fed up of hearing drip drip drip !

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Re: ROOFING EAVES DETAIL

Postby Meccarroll » Thu Oct 05, 2017 6:25 pm

Deep flow is used for flat roofs because the plan area of the roof often shows greater and so collects more water, pitched roofs do not always need deep flow. You should be able to check with the guttering manufacturer who could do the calculations based on plane area.

Mark


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