Cladding finishing above windows- rain?

[daunker]

I've Siberian larch cladding and reveals, but now it's up I'm concerned water could run down the cladding, particularly the grooves and hit the reveal where it might track back towards the building and window.

 

Just wondered what my options are here, I do have extra larch, so could have it oversail the head but was also thinking I could put drainage holes in the reveal or could plane back the reveal so that the cladding is further out Or could fit a metal drip (zinc as per roof) above the reveal or any suggestions/recommendations very welcome..!

[markc]

I would have taken the cladding over the reveals, not flush - unless the reveal slopes outwards like a cill

[Roundtuit]

I used a strip of lead flashing folded up behind the cladding and dressed half way down the front of the top reveal lining.

[Russell griffiths]

Should have a folded trim behind the timber to prevent water tracking backwards. 

[Ian]

Good link here to a Scottish Gov publication:

https://www.gov.scot/publications/timber-cladding-scotland/pages/13/

[ProDave]

I am making the "box" around the window end flush with the inside face of the cladding, and the cladding then continues down in front of the "box" with the bottom edge of the cladding ending lower than the "box" and cut an an angle with the lower edge t the front.

[Gone West]

On my timber cladding I ran it down in front of the reveal and left a 3mm gap between the reveal edge and the cladding as a drip gap.

[SimonD]

It looks like such a typical English cladding detail.

 

Do you have any roof overhang? From the photo it looks to me like there is just about 25mm or so for the fascia and then your guttering, but I may be mistaken? If not, then you are going to be fairly exposed. Timber cladding should always have a generous roof overhang for long term performance, but that often gets overlooked, by designers and builders alike in this country.

 

The issue with water ingress is not just water running down the outside of your cladding and tracking back into the fabric at the reveal but also ingress to the inside of the cladding (e.g. from wind driven rain) being able to get out. Therefore, if you add some flashing, it should ideally be installed across the ventilation gap behind the cladding and tucked under the membrane. I notice from your photos that there doesn't seem to be any bottom ventilation provision at the reveal.

 

If you're so inclined, you could remove the reveals and take a look to make sure the top of the window has been properly finished for full weather protection within the frame (behind the cladding) and then rip down the reveal board to leave a gap large enough to both provide bottom ventilation to the cladding and allow any water to drain out.

 

I'm sincerely hoping that what looks like a bead of silicon between the window frame and reveals isn't your only layer of weather protection - I'd suggest it would have been a neater and longer lasting finish to have used an expanding foam tape between the window frame and edge of the reveal board - this would take up the natural movement you're going to get with the timber boards and would make it easy to remove the reveals in the future in case of essential maintenance.

 

 

 

Edited July 2, 2021 by SimonD

[daunker]

1 hour ago, SimonD said:

Do you have any roof overhang?

The roof is standing seam zinc, and so it folds into the gutter - so I think the gutter also acts as an overhang. Except at the gable ends - where the overhang is only as you say - the fascia with no guttering.

 

I notice from your photos that there doesn't seem to be any bottom ventilation provision at the reveal.

The battens behind the cladding (and also battens for the cement board below) - have holes drilled repeatedly (vertically). Would this give ventilation to the whole space? There is insect mesh, but no other membrane, should there be?

 

If you're so inclined, you could remove the reveals and take a look to make sure the top of the window has been properly finished for full weather protection within the frame (behind the cladding) and then rip down the reveal board to leave a gap large enough to both provide bottom ventilation to the cladding and allow any water to drain out.

 

The reveals were fitted before the windows, so the windows have only been finished by foaming the gap from the inside, then there is silicon between the reveal and the frame?

 

Quote

 

I'm sincerely hoping that what looks like a bead of silicon between the window frame and reveals isn't your only layer of weather protection - I'd suggest it would have been a neater and longer lasting finish to have used an expanding foam tape between the window frame and edge of the reveal board - this would take up the natural movement you're going to get with the timber boards and would make it easy to remove the reveals in the future in case of essential maintenance.

Hmm... as per above, it is only the silicon. The windows are sited on the outer blockwork, and then were foamed from inside.

 

 

Edited July 2, 2021 by daunker

[SimonD]

On 02/07/2021 at 11:08, daunker said:

The battens behind the cladding (and also battens for the cement board below) - have holes drilled repeatedly (vertically). Would this give ventilation to the whole space? There is insect mesh, but no other membrane, should there be?

 

The reveals were fitted before the windows, so the windows have only been finished by foaming the gap from the inside, then there is silicon between the reveal and the frame?

 

Hmm... as per above, it is only the silicon. The windows are sited on the outer blockwork, and then were foamed from inside.

 

Okay, in my view those details are unfortunate. Who did the detailed designs for this? The purpose of the cavity behind a facade, whether cement fibre board or cladding is a combined for both ventilation and drainage of water ingress. Normally you'd install counter battens to achieve this (if you really wanted to follow best practise, those counter battens would be machined with an angle at the top to shed water). With holes drilled in the battens you won't know if there's sufficient ventilation and it's unlikely to provide necessary drainage - I find this a bit of a bizarre way to to this as the holes will undermine the structural integrity of the battens and it must have taken ages and been a lot of work!

 

With the windows, they should really have been fully installed to be weatherproof behind the cladding.

 

At present you have several areas of risk, one of which is definitely the top of the windows. At the top of building openings, cladding should allow for bottom ventilation of the cavity and drainage (sometimes this is changed due to fire spread risk).

 

There's probably little you can do now about the battens, but it's worth investigating behing the reveals and making good around the windows if that's possible.

[daunker]

The reveals are only screwed on so easy to replace. To get this right by the sound of it I need to:

1. Replace silicon around reveal and window edge with expanding foam tape.

2. Between window frame and blockwork where currently there is expanding foam, to make weatherproof with?

3. Recess the reveal top and sides and oversail the cladding.

 

Left the carpenters to it- as they've done cladding a number of times before. Sorry I am mistaken I have found some photos of install.. pleased to confirm it is counter battened think it is just the bottom timbers at base of cement board that had holes drilled for the ventilation/drainage. 

[SimonD]

13 hours ago, daunker said:

The reveals are only screwed on so easy to replace. To get this right by the sound of it I need to:

1. Replace silicon around reveal and window edge with expanding foam tape.

2. Between window frame and blockwork where currently there is expanding foam, to make weatherproof with?

3. Recess the reveal top and sides and oversail the cladding.

 

Left the carpenters to it- as they've done cladding a number of times before. Sorry I am mistaken I have found some photos of install.. pleased to confirm it is counter battened think it is just the bottom timbers at base of cement board that had holes drilled for the ventilation/drainage. 

 

That looks a bit more like it. Yes, that's counter battened.

 

You can seal the windows with either a sealant - Soudaseal 215LM is made for window and door connections for example - or an expanding foam tape. It'll depend on the acces you have and the gap space. I would be inclined to also use an expanding foam tape between the window frame and reveal as a primary weather barrier. At the top of the window opening, ensure there is a ventilation and drainage gap for any water to drain from behind the cladding.

 

Others on here have given some really good suggestions about ways in which you can finish the reveals around the windows. The cladding I've just installed myself actually uses reveals similar in design to yours, which I chose because I liked the look. Mind you, I do have large roof overhangs over all my openings (500mm on one side and up to 1000mm on another). Here, however, is a nice example of the suggestions made by @markc, @ProDave, and @Gone West, which is no doubt better from a weather protection perspective:

 

 

HTH

 

[junglejim]

@ProDave @markc @Gone WestReally useful reading this. I’m about to order cladding materials and will be fitting in a couple of weeks. I’m using a mixture of horizontal and vertical cladding. I like the over sail suggestion at the top. That makes sense. I’m curious whether there is also a head flashing detail that needs considering.

 Also for the side reveals I hadn’t thought of over sail. Is there an advantage to this? I’m also wondering if there are any different considerations for horizontal cladding? 
thanks

Edited December 5 by junglejim

[Gone West]

12 hours ago, junglejim said:

 Also for the side reveals I hadn’t thought of over sail. Is there an advantage to this?

I didn't oversail the cladding on the side reveals, only at the top. I used the same detailing for both horizontal and vertical cladding.

[junglejim]

On 01/07/2021 at 17:39, Roundtuit said:

I used a strip of lead flashing folded up behind the cladding and dressed half way down the front of the top reveal lining.

That’s interesting. Did you take that behind the battens ands back to the membrane? Do you have any pictures you’d be happy to share? Ta

[Roundtuit]

2 hours ago, junglejim said:

That’s interesting. Did you take that behind the battens ands back to the membrane? Do you have any pictures you’d be happy to share? Ta

Yes, folded up behind the battens.  It was on to blockwork with a cavity, so I didn't bother with a membrane.  I'll be doing another one in the not-to-distant future on a timber frame and plan to slide the lead under the membrane. You can just see the lead on this:

 

 

[junglejim]

Thank you. That’s helpful.

 Does you find it interfered with the battens at all or pushed out the cladding?