Window to french door = NO  


hi all


we had 2 different window fitting companys to give us a quote to remove the big window in kitchen then replace with french doors. both have said no. the head installation manager at crystal windows even said they wont do it in case the side of the house falls down. after i finished laughing he said the concrete is 'supporting concrete' and cant be removed? nearly every house in our road has had the window replaced with doors. anyone know anyone in essex who does know what they are talking about or does he have a point?


many thanks


Hello and welcome to our forum.

I'm sorry to hear that you're facing issues and I understand that this can be frustrating but I do think that both window companies in this case are erring on the side of caution because the potential issue that they have described can and does happen I'm afraid.

I have undertaken several patio door installations myself including one on a property that I own, and one on a friends house. It was during the installation at my friends house that this very issue occurred, causing a large area of the render to fall away adjacent to the window opening.

In my friends case however, this wasn't a major issue as the house was due to be externally insulated a few days later. We simply removed the damaged section and replaced it with OSB board which was a suitable carrier for the solid external wall insulation panels. Once fitted, the area was rendered and looked as good as new. We were fortunate in this respect, but had the property not been due to receive insulation, we would have needed specialist help to repair the wall.

With the above scenario in mind, I must point out that in our case, there were tell tale signs indicating that the wall might fail prior to starting the installation. The most notable sign was the presence of long horizontal cracks running through the existing render. Some of the cracks were several feet in length and when the render itself was tapped with the handle of a screwdriver, it sounded hollow in places. This indicated that the cement render had separated from the steel carrier mesh, causing it to become unstable. This is often caused by poor maintenance as water is allowed to seep into the fine cracks where it freezes and expands causing further worsening damage.

Your property may not have any visible defects such as those mentioned above, but even so, it is important to understand the structure of your wall, compared to a standard brick wall.

In the case of a single skin brick or cavity wall, the required opening can be cut out quite easily using a stihl saw which allows for the new doors to be dropped directly into place. The frame can be fixed directly to the brickwork using frame fixing screws and sometimes a small amount of drywall plasterboard work may need to be completed inside the property to make the work good.

In a BISF house, the render wall is effectively self supported on thin steel mesh ribs, If these ribs become corroded due to water penetration, the ribs or mesh become weakened and the cement render can separate and become loose. When this material is cut, using a stihl saw or grinder, the cut will ether be clean and stable or jagged and rough if the render is in a poor state. The problem is you won't really know how the wall will respond until you start to cut it. 

You will also need to install a framework of timber battens around your new opening to receive the frame fixing screws as without this, there is no solid surface to anchor the screws.

Once completed and installed, you may need some remedial work to be carried out to the exterior render and any exposed timber framework would need to be rendered over too but this should not be a major job. 

Take a look at our post regarding our DIY patio door installation as it may give you a better idea of what is involved.

In general, I think windows and door fitters prefer straightforward installations that may only take a few hours to complete. In our case, it took us two days including framework etc. We purchased a ready made off the shelf set of doors in order to keep costs low. As the unit was smaller than a made to measure unit, we had to install a little more framework, but it wasn't particularly difficult. You may be better off going on a similar route but employing a builder or DIY professional as opposed to a window fitter. They may be able to allow more time to complete the job and to make good any repairs without breaking into a sweat if some of the wall does break away. Either way, it may be wise to factor this into your budget before starting work.

Let me know what you think.





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