Adding a window - PP & structural integrity

[electrogear]

Hi,

I’m wanting to change the external appearance of my house as I don’t like the 1960’s cream bricks so I was hoping to render/cedar clad the front and add an additional window. I’m not in a conservation area and it’s not listed (no surprise there).

Reading the guidance on my local authority planning page it doesn’t sound like I need planning permission, but will there need to be structural considerations since the majority of the support for the upper level will be shifting to two lintels with a column in the middle?

Also any thoughts on the design? I threw it together tonight so it’s only a first draft.

 

[robinbanks]

Also any thoughts on the design?

Go the whole hog?

 

[electrogear]

Go the whole hog?

View attachment 301496

Haha. Nice design but so many issues with applying it to our bog standard house! Think this looks a little better…

 

[robinbanks]

I prefer that one (less busy, less "sad-robot"), though I think 4 panes per window might be a bit much unless using a slimline alu profile (and even then..)

 

[electrogear]

I prefer that one (less busy, less "sad-robot"), though I think 4 panes per window might be a bit much unless using a slimline alu profile (and even then..)

We’re going for flush casements (“in frame”). Each window is 2.4m wide so they are big windows. All of our neighbours who replaced their windows 1990-2010’s have gone with 3 panes but the ones in the last 5 years who’ve rendered have gone for 4 panes and it looks good IMO.

 

[electrogear]

I prefer that one (less busy, less "sad-robot"), though I think 4 panes per window might be a bit much unless using a slimline alu profile (and even then..)

After much deliberation and assessment of the design and costs I think you are right!

4 panes increases the cost, as does adding more openers and top opening windows. The best balance of cost/design/functionality seems to be 3 panes with the left and right window opening, and no top-openers, however with 3 panes you can’t have equal sized panes if you want opening windows as the maximum width for an opening pane is 700mm.

To get more light into the downstairs front room (which is the Full width of the house) it would make sense to open the window to one long opening. It has the added benefit of knocking about £400 off the cost, but I’m not sure if it adds to the “sad robot” effect you mentioned. Also, because of the width, you can’t have any openers on any of the windows…

the only way to get openers with the above design on these frames is to go for 2 big toughened glass windows in the centre and 700mm opening panes either side…

(cost is for windows only - not including building work for new downstairs openings)

 

[robinbanks]

Does the "one long opening" cost factor in the steel beam needed above the window? For shorter spans, it's likely off the shelf lintels can be used but for long ones you could be into thousands for a bespoke fabricated pair

I don't recall ever reading anything about panes larger than a certain size having to be toughened, only panes within a certain distance of the floor. Where did the requirement for the big panes adjacent the openers being toughened come from?

Edit; just caught the last sentence.. The 400 or so difference in the windows would be swallowed up quite easily in the extras needed for a long run

 

[electrogear]

Does the "one long opening" cost factor in the steel beam needed above the window? For shorter spans, it's likely off the shelf lintels can be used but for long ones you could be into thousands for a bespoke fabricated pair

I don't recall ever reading anything about panes larger than a certain size having to be toughened, only panes within a certain distance of the floor. Where did the requirement for the big panes adjacent the openers being toughened come from?

Edit; just caught the last sentence.. The 400 or so difference in the windows would be swallowed up quite easily in the extras needed for a long run

The Deceuninck frames I’m ordering automatically switch to toughened glass for panes 1890mm and above - not sure why! I know it’s <800mm from the floor they have to be toughened which is why I plan to make the new windows smaller in height (the existing one is 700mm from the floor). If I go for top-opening windows it increases the allowable width to 1200mm on the outer panes and thus removes the need for toughened glass on the larger (now 1500mm) panes, taking the cost back down:-

I’m going to ask the builder to quote me for both jobs - creating a wide opening or two smaller ones. I’d assume it’s going to be more labour for two openings because he’ll have to build a brick pillar in the middle.

The off-the-shelf 2.7m lintels (27KN) are around £330 each. I think the 6.1 metre beam I had made for the back or the house a few years ago was about £1100.

Cost isn’t the only factor - if it’s going to look better with one opening and the builder’s quote isn’t ridiculous then we will probably go that route.

 

[^woody^]

Cladding is only PD if it matches the existing materials.

New windows are PD as long as they meet the PD criteria - overlooking, openers and suchlike.

 

[electrogear]

Cladding is only PD if it matches the existing materials.

New windows are PD as long as they meet the PD criteria - overlooking, openers and suchlike.

Although the cedar cladding/render is obviously nothing like the 60’s cream brick we’re covering up, I’m hoping we can get away with it on the basis that it will match the cedar cladding right across the back of our house which we did with BC sign off 4 years ago.

The new opening should be ok. We look out into the street, but not overlooking any gardens or neighbouring properties. They’ll have openers with fire hinges and 8000mm2 trickle vents as per the new 2022 regs.

 

[^woody^]

What does "getting away with involve"? Doing it and hoping for the best or getting it verified via a LDC or formal planning application. The render too by the look of it a that is deemed the same as cladding.

Also be aware that building regs part L1 will apply - altering more than 25% of the wall area, so consideration for upgrading thermal insulation is a requirement

What are those prices for, just the cladding materials?

 

[electrogear]

What does "getting away with involve"? Doing it and hoping for the best or getting it verified via a LDC or formal planning application. The render too by the look of it a that is deemed the same as cladding.

Also be aware that building regs part L1 will apply - altering more than 25% of the wall area, so consideration for upgrading thermal insulation is a requirement

What are those prices for, just the cladding materials?

I still have contact info for the last planning officer we used and he said if we need to run anything by him then we can so that will be my next step. I’m not looking to “hope for the best” or anything silly.

I would like to add more thermal insulation anyway as I don’t think our existing polystyrene cavity wall insulation is very efficient.

The cost is just for the windows - I know it doesn’t capture the whole cost, it’s just a start, and as I go about getting the various prices and quotes for the other bits it will be handy to know how much the different types/sizes of window cost.

 

[electrogear]

sorry, the bit about 25% of the wall area - are you talking about the glass? Doesn’t that only apply to extensions? If it applies to existing buildings for new openings, then where do they determine “wall area”? - of the whole house? All four walls of the room in which you’re putting a window in? Just one wall?

 

[^woody^]

Seems cheap for just the frames. Is that supply and fit?

Regulations aside, I would look at proper images of similar houses with similar works. What is happening around the sides and with the bargeboards and fascia? This type of work needs to be considered in conjunction with other aspects of the building and not in isolation as a "front elevation", and there is a risk of it not looking right, and small design details can make a massive difference as to whether a design works or not.

Colours of the other components, rough or smooth render, width of the cladding, or even whether repetition off window sizes is desirable - they look a little dominant in those knock-ups, may be different in a real life/photo though.

 

[^woody^]

sorry, the bit about 25% of the wall area - are you talking about the glass? Doesn’t that only apply to extensions? If it applies to existing buildings for new openings, then where do they determine “wall area”? - of the whole house? All four walls of the room in which you’re putting a window in? Just one wall?

No, read up on part L1 - its 25% of a wall (elevation) or roof or floor that is being renovated