Cavity closers - building regs

[GJD]

I have a refurbished property with new build walls & replacement aluminium double glazing which I have problems with. Nearly all windows have new brickwork around them & some are new (replacing a garage) I think that the builders/installers have not put cavity closers in or sealed the cavities & I'm having this checked.

I've read Building Regs Part L (?) and cannot find a simple answer! Can anyone tell me whether this should have been covered by BR as the rest of the refurbishment was?

 

[noseall]

You will only require cav closers as long as you have a cavity (gap) to close.

In reality 'cavity closure' is just a building term. In the olden days cavities were closed with masonry and DPC and still can be as long as aerated blocks are used. Proprietary closers are used in today's building in preference over masonry closing and in conjunction with specific UPVC window fixing systems.

Was the internal masonry rebuilt along with the external brickwork?

 

[GJD]

Thanks. Here's some more info which answers your points (hopefully)

The property is a 1980's bungalow which has been completely renovated & refurbished. New window openings, door openings etc have been constructed with all internal walls rebuilt where necessary. Existing double glazing (UPVC) was removed and new aluminium DG installed. All approved by the local council building control as requiring building regs approval only.

The fitting instructions for the DG state that all cavities must be either closed or sealed with insulating material so the thermal break in the windows will work. I am having to have a camera inserted into every window & door cavity to confirm this as the aluminium frames are extremely cold when it is cold outside, and condensation etc. because of the cold frames.

The point is - if the cavities should have been closed under building regs (as per new property) then the builder should have done this & building regs inspector should have approved it. (I have a building regs certificate) If not, then the DG installer should have done it as it is quite specific in the installation instructions.

Correcting this on 13 windows, a bi-fold door & French Doors will not be cheap, or clean, nor simple! I need to understand what claims i have on who!!

 

[freddiemercurystwin]

What did the drawings say?

 

[noseall]

The fitting instructions for the DG state that all cavities must be either closed or sealed with insulating material so the thermal break in the windows will work. I am having to have a camera inserted into every window & door cavity to confirm this as the aluminium frames are extremely cold when it is cold outside, and condensation etc. because of the cold frames.

The frames will still be cold when its cold outside, irrespective of cav closers. It is the design of the frames which counters cold bridging through the frame itself. Most decent ally frames have thermal beaks to control this as per modern bi-folds etc.

Cav closers will stop transfer of cold through the masonry and not through the frames, though they do compliment each other.

The point is - if the cavities should have been closed under building regs (as per new property) then the builder should have done this & building regs inspector should have approved it. (I have a building regs certificate) If not, then the DG installer should have done it as it is quite specific in the installation instructions.

Cav closers are not necessarily part of BC checking process though they do comment on them if they are visible during an inspection.

the DG installer should have done it as it is quite specific in the installation instructions.

Correcting this on 13 windows, a bi-fold door & French Doors will not be cheap, or clean, nor simple! I need to understand what claims i have on who!!

I would say it is the job of the builder to install CC's prior to the fitters arriving.

 

[^woody^]

Walls are the responsibility of the builder.

Cavity closing of reveals is not normally stated as something that is checked by the inspector. But I have a suspicion that the checking of DPC is a statutory check, and so checking the reveals should be too.

But rectifying is a simple thing involving a can of expanding foam, and DPC if non there already

 

[GJD]

Thanks all for your replies.

I've now had a camera look into all the cavities below the DG frames & there is no sign of any cavity closers, insulating foam under the windows, nor any insulation in the cavities. (The refurb included insulating plasterboard on every external wall). On some windows the window board can be seen above the cavity. The majority of windows are new external brickwork and internal blockwork.

It's pretty clear that the lack of cavity closers or proper insulation is causing a cold bridge which is negating the thermal break in the windows & causing cold spots. Thus cold frames & condensation etc.

My take is that the builders should have dealt with this as they were (obviously) aware that aluminium frames were being installed. The DG installer should have followed the instructions from the manufacturer & ensured either cavity closers were there or the cavities were insulated.

The proper course of corrective action in my opinion should be to remove each window, insert cavity closers underneath each window & seal each reveal, re-install & make good internal and external damage & decoration. This will be very disruptive & expensive, but anything less may not work properly. I'll be taking this up with the builders & DG installer.

The outstanding question I have is regarding the Building Regs inspector. Surely they must have a responsibility to ensure that the correct standards are applied by the builders? What's the Part L (if that's the right requirement for a refurb?) standard?

 

[^woody^]

It's pretty clear that the lack of cavity closers or proper insulation is causing a cold bridge

That can't be clear. Air is an excellent insulator and there won't/can't be a thermal bridge.

There is no need to remove any windows to rectify this. None at all.