It is essential therefore that great attention is paid to the detailing and installation of windows and doors.  In my opinion this is often not happening and litigation as a result of the consequential leaks is a natural and expensive result.

Cavity construction, pressure equalisation of the trim cavity and even the most excellent flashing system will not allow for the inevitable leaks at the window or door junction that I want to focus on here.

This article is intended to bring to the attention of builders yet another issue that is affecting window and door installations and has created a new cause and reason for window and door leaks in aluminium joinery installations.

The new leakage point has been brought about by the extensive use of double glazing to comply with H1 requirements and the need to cantilever windows and doors out beyond the  framing line as much as 50mm.This occurs  with both direct and cavity construction.

What is needed is full window support along the length of the window and door.

This requirement in the main is not being insisted upon by Building Consent Officers nor is it being widely enforced on site.

This is not entirely an oversight of the BCA’s as E2/AS1 is not clear on the essential requirement to provide critical support in any of the window drawings.

If you look at figures 76, 81 – 86, 90.95,99,115,116,127 and 128 of E2/AS1 which all relate to window installation, there is not one drawing that shows a support bar, let alone states that it is an essential part of the window installation.

There is however in note 3 attached to all these drawings this statement;

“Where support brackets are required by the window manufacturer to carry the frame and glazing loads they must be supplied as an integral part of the window installation and installed to the window manufacturer’s recommendations.”

This lack of clarity regarding the importance of supplying the window support has raised a potential gold mine for lawyers with future new litigation claims for early failure of window and doors which do not have the required support as stated in Note 3 mentioned above.

The window manufacturers themselves are in a state of confusion as to what is needed. A builder cannot afford to be confused on such issues as they are the prime respondent in any leaky home claim.

In my discussions with the WANZ technical committee on the issue of support to windows their answer was clear and adamant. “All windows require full support !”.

This is not happening. Where support is being provided it is inadequate or contrary to WANZ’s own recommendations to their members.

The WANZ website is very clear on the matter however as stated in this excerpt taken from their site on July 10 2009.

Cill support has often been a crucial part of window installation, but has often been overlooked. The detrimental effects of not having cill support bars are not immediate but usually manifest themselves over a period of time, and hence we see indifference in using them. Most joinery is fixed to the building framing, through the jamb liners thereby creating a cantilevered action. This action stresses the corners, mullion joints, frame/liner connection and eventually compromises their integrity and in turn the integrity of the whole window system. With double glazing becoming more common place, the weight is practically doubled and the problem is further compounded. The combination now of both double glazing and cavities becoming the norm, the stresses on joinery has been increased.    .

With this in mind, all windows and doors irrespective of their size and construction/cladding type must have cill support (emphasis mine)

……These WANZ Support bars are available through your local window supplier and must be used the full length of the window/door. (Emphasis mine)

Can’t fit window support with direct fix construction

Let me ask this question at this point. How is it possible to fit a support bar to a direct fixed installation where there is a sill tray! Answer, it is not possible. That point alone should put an end to the entire practice of direct fix! The cheapest insurance available is the price of cavity construction at a cost of approximately $1,000 to batten out an average sized house.

On my independent inspection of window and door installation, I discovered that often the support bar or brackets did not support anything at all! A bit like the many huge beams I have seen in roof spaces where load bearing walls have been removed and a beam installed on top of the ceiling joists but not landing on any load bearing walls. In other words the support bars have added expense for no purpose whatever.

In many of the remediated leaky homes where existing window and door joinery remains, (a practice I do not recommend) the now essential support blocks were never fitted by the window manufacturer because no one had thought of window support. It is clearly impossible to provide support via a WANZ bar or by some other means, if there is nothing to support!

Builders face litigation if windows and doors leak due to sagging and the opening up of mitres and mullion connections which cause leaks well inside the framing line. (A cavity won’t help)

All aluminium windows and doors need to be properly supported as stated (unclearly) in E2/AS1 and emphatically by WANZ.

For the answer to this issue see opposite (page or… page number?) (I will have the answers in the Flashman Full page advertisement.

How do you fit a sill tray as required by E2/AS1? Answer…you cannot!

E2/AS1 from DBH website TIF file conversion from original PDF of a cavity construction sill detail

Question: Where is the window support?

E2/AS1 from DBH website TIF file conversion from original PDF of a cavity construction sill detail

Question 1.  Where is the window support?

Question 2. How can you fit a support bar here with the sill tray/flashing impeding the support bar?

Notes to Editor

I have included here tif files of sill details from E2/AS1 to show what appears in the compliance documents and why there is confusion as to the need or no need for window supports.

WANZ stipulate that you MUST have FULL support and many BCA’s just pay no attention to this as the E2/AS1 documents and drawings do not show a support bar at all. I think the article HAS to show these drawings to relate the reasons why there is confusion. If we compare the WANZ details to the E2/AS1 details the cause of the confusion is rampant. If they can be shown side by side and the question asked-

Spot the reason for confusion?

It is a good question and makes the article work better, I know there is a bit of space needed but the cost of ignoring this issue warrants the space in my view but that is up to you of course.

Confusion over responsibility is the biggest issue with regard leaky home litigation.  I am attempting to nip in the bud another reason for further confusion and litigation over lack of clarity on this issue to support or not support.

It is obvious that support is needed and must be integrated into the window installation on every occasion whether direct or cavity construction.

Mike Anticich

Director

Flashman Flashing Systems Ltd

PO Box 346 Kaiapoi 7644

Christchurch

Tel 03 327 22 72

Mobile 027 55 11 897