Check Reveals

[Mr Blobby]

I like the idea of check reveals but are they worth the effort in a block cavity build where the external render will overlap the window frame in any case.

 

Are check reveals required under Northern Ireland building regs as they are in Scotland?

 

If using check reveals then I would still fix windows with straps to the inner leaf I think, with check reveal cavity closers (if available for 250mm cavity) instead of DPM.

 

Are the windows more securely fastened in a check reveal, being pressed up against the outer leaf?  Is there less room for error on the window sizing/installation?  Is there a better seal against the outer leaf?

 

How much extra effort to build check reveals and do the benefits justify the effort ? 

 

 

 

 

 

[joe90]

54 minutes ago, Mr Blobby said:

Is there less room for error on the window sizing/installation? 

Yes

 

54 minutes ago, Mr Blobby said:

How much extra effort to build check reveals and do the benefits justify the effort ? 

I did check reveals and love the results, I fixed to the outer leaf with stainless brackets and screws. As ours was a brick build I got the brick layer to use whole or half bricks and sized the windows to match overlapping by 20mm each side.

[dpmiller]

Don't think there's an option in NI, no.

[ETC]

You’ll find that many brick layers in NI will use check reveals if only by 15-25mm. Many tend to use check reveals so that they can close the cavity with calcium silicate board before the windows are fitted.

[Mr Blobby]

1 hour ago, dpmiller said:

Don't think there's an option in NI, no.

 

Do you mean that check reveals are mandatory in Northern Ireland ?

 

From what I've read on the NHBC 2011 guidelines it says that check reveals should be used in Northern Ireland and Scotland but I can't seem to find anything more recent about it. 

 

[ETC]

They’re not - no. Not by BC. Might be asked for by NHBC but not BC.

Edited November 9, 2022 by ETC

[Mr Blobby]

18 minutes ago, ETC said:

You’ll find that many brick layers in NI will use check reveals if only by 15-25mm. Many tend to use check reveals so that they can close the cavity with calcium silicate board before the windows are fitted.

 

That's very interesting, and good to hear.  My previous, very limited experience of NI bricklaying, saw return blocks at the reveals that seems pretty standard practice here.  I definetely don't want that on this project.

 

Our architect has supplied construction detail for a section of the window to show the cill with cavity closer at the bottom of the window but no detail for the reveals (other than the plans that appear to not have check reveals).

 

I'd be very happy with a 20 mm check reveal if that is standard practice here that the brickies are happy to oblige with.

 

Calcium silicate board in the reveals?  With DPM behind in the reveals?  Better than cavity closers?

 

Edited November 9, 2022 by Mr Blobby

[Mr Blobby]

24 minutes ago, ETC said:

They’re not - no. Not by BC. Might be asked for by NHBC but not BC.

 

I can see a conversation about this with my builder then.  Thanks.

[JackofAll]

Sorry to piggy back on thread but am interested in check reveals, am thinking ply box(300 cavity) butting up to outer leaf, windows stepped back few mm to allow for compriband or some such tape with windows strapped to box and box fixed to inner leaf like Iceverge did(correct me if wrong) or window sits proud of box with tape contacting outer leaf? is there a better or perhaps easier method?

[Dave Jones]

a proper cavity closer that is tied into the brickwork as it goes up is much better. Bricky will like it as he wont have to use a level on any of the windows. 

 

https://subframes.co.uk/cavity-closers/cavalok/

 

[JackofAll]

On 15/11/2022 at 07:56, Dave Jones said:

a proper cavity closer that is tied into the brickwork as it goes up is much better. Bricky will like it as he wont have to use a level on any of the windows. 

 

https://subframes.co.uk/cavity-closers/cavalok/

 

They look the business but imagine they'll be alot more expensive than osb/marine ply when taking all openings into account, anyone else use them instead of osb/ply?

[Iceverge]

Sorry for the late reply. Just saw this.

 

Built the two leafs individually here. 150mm setback lateral for the inner leaf laterally (for splayed reveals) and about 25mm vertically. 

 

Fitted the Windows to the outer leaf resting on Killeshal  type "H" precast window sills with concrete screws and brackets. There was about 20mm window bearing on the sill and 60mm floating over the cavity. 

 

Then made self supportive window boxes from the inside out from 18mm OSB. Just pushed against the inside edge of the window and concrete screwed to the internal skin. 

 

The window doesn't bear on the OSB and the OSB doesn't bear on the window. 

 

Then used plenty of airtight tape to join the OSB to the window and airtight paint to join the OSB to the inner leaf. 

 

I'm not sure I'd do it this way again. It took ages to make the OSB although it didn't get exposed to rain throughout.  Probably better to make up the window boxes first. And use external galvanized brackets on the corners. That way they would be strong enough to hold the Windows.

 

Also they measured the windows in the conventional way. IE exactly the same or a little smaller than the external opening. As we built the inner leaf bigger I wanted the external leaf to overlap by 20mm but this didn't happen.

 

Compriband would be what I'd use next time too for a good external Windtight layer. 

 

 

 

 

If you use an @ before my username it will alert me next time by the way.

 

 

[JackofAll]

On 19/11/2022 at 22:35, Iceverge said:

Sorry for the late reply. Just saw this.

 

Built the two leafs individually here. 150mm setback lateral for the inner leaf laterally (for splayed reveals) and about 25mm vertically. 

 

Fitted the Windows to the outer leaf resting on Killeshal  type "H" precast window sills with concrete screws and brackets. There was about 20mm window bearing on the sill and 60mm floating over the cavity. 

 

Then made self supportive window boxes from the inside out from 18mm OSB. Just pushed against the inside edge of the window and concrete screwed to the internal skin. 

 

The window doesn't bear on the OSB and the OSB doesn't bear on the window. 

 

Then used plenty of airtight tape to join the OSB to the window and airtight paint to join the OSB to the inner leaf. 

 

I'm not sure I'd do it this way again. It took ages to make the OSB although it didn't get exposed to rain throughout.  Probably better to make up the window boxes first. And use external galvanized brackets on the corners. That way they would be strong enough to hold the Windows.

 

Also they measured the windows in the conventional way. IE exactly the same or a little smaller than the external opening. As we built the inner leaf bigger I wanted the external leaf to overlap by 20mm but this didn't happen.

 

Compriband would be what I'd use next time too for a good external Windtight layer. 

 

 

 

 

If you use an @ before my username it will alert me next time by the way.

@Iceverge

When you say 150mm laterally do you mean the inner leaf was 75mm bigger each side? Be interested to know what the dimensions of the brackets fitted to inside of outer leaf. My only concern with the wood is two thirds of it would be unsupported unless a bracket similar to that of the cill is fitted to outside of inner leaf? 

 

Had a look at killeshal website, they have sill supports but only appear to go 200mm max cavity. 

 

External face of window fitted with compriband butted to inner face of outer leaf?

 

Edited November 21, 2022 by JackofAll

[Mr Blobby]

On 15/11/2022 at 07:56, Dave Jones said:

a proper cavity closer that is tied into the brickwork as it goes up is much better. Bricky will like it as he wont have to use a level on any of the windows. 

 

https://subframes.co.uk/cavity-closers/cavalok/

 

 

Cavalok closers look grand, but are they available for 250mm check reveals?

[Iceverge]

@JackofAll Have a look at these posts. See if it makes more sence?

 

 

[JackofAll]

On 21/11/2022 at 19:58, Mr Blobby said:

 

Cavalok closers look grand, but are they available for 250mm check reveals?

They go up to 300mm AFAIK.

[JackofAll]

On 21/11/2022 at 20:01, Iceverge said:

@JackofAll Have a look at these posts. See if it makes more sence?

 

 

Lots of info in that thread, much appreciated. I was always curious about trays above openings. Never have I seen weep holes above windows/doors. Come to think of it never seen them lower down below ffl either so always wondered what the point was apart from keeping moisture away from inner leaf, where's it suppose to go. Interesting idea re. pvc angle. Fair play for the level of detail offered up in your posts and what you would do differently, solid gold.