Change To Sunroom Windows After PP Granted.

ShiverinEskimo

We've recently been granted planning permission and are going over our plans getting them ready to obtain quotes.

Our design went in with windows which wrapped around the sunroom with each window seperated only by steel posts and going from cill to ceiling.

In hindsight this design is likely to cause a decent bit of heat loss through the metal and I would rather space the windows with block cavity walls to allow me to properly insulate the sun room.

As this would form a change to the look of the house slightly compared to the submitted design am I risking violating the planning permission or would it be considered a minor enough change to not cause problems?

mickdw

You certainly need to talk to the planners about this IMO. If they consider it a minor issue, they can cover it by way of letter meaning that you are good to go.
This also goes to show that nowadays with the current energy regulations that you cannot simply design a house and then try and make it work with the regulations.

Mellor

ShiverinEskimo wrote: »

In hindsight this design is likely to cause a decent bit of heat loss through the metal and I would rather space the windows with block cavity walls to allow me to properly insulate the sun room.

The sunroom should really be thermally separte from the house. The house insualted as if it wasn't there. Separtely heated etc. Then its just a buffer space to improve the heat loss of the main house.

fclauson

Mellor wrote: »

The sunroom should really be thermally separte from the house. The house insualted as if it wasn't there. Separtely heated etc. Then its just a buffer space to improve the heat loss of the main house.

Or as heat capture device for the MHRV - it will warm up quicker and prehaps you could make use of the heat from it to keep the rest of the house warm

discuss it with a good MHRV supplier as to how you can use this type of space

ShiverinEskimo

Cheers mellor. What about the door in though? Won't the door always be a weak point?

I was thinking even if I seperated the windows by a single block's worth of cavity wall and then installed the windows as I would the rest of the house it would be consistent and as fclauson says could be used to the advantage to add captured heat into my HRV.

fclauson

You might want to put the challenge to the window suppliers - how do you get a thermally efficient conservatory

one option might be to use "curtain walling" like on the large farcarde of shops

there is a system (I will PM you) which externally would be all glass with small infills and internally is 4 by 2 or 6 by 2 vertically on edge as support - looks nice - thought about it for our porch - which is three sides glass.

this would give you a fully glazed effect - which is thermally efficent.

PHPP recongnise curtain walling as being much better psi values (i.e. thermal loss at the edges) than normal windows because basically its all glass to the outside.

Mellor

ShiverinEskimo wrote: »

Cheers mellor. What about the door in though? Won't the door always be a weak point?

Nope the door is detail as the final point.
Thinl of it as the sunroom built as an extension (in terms of detailing, not planning)

ShiverinEskimo

But that would mean leaving it closed off during times the house is being heated in the winter. As it is it's kind of doubling up as a bit of a living/dining area off the kitchen so I don't think it's feasible or practical for me to keep exclusive from the main house.

The blocks replacing the posts would allow me to wrap the windows with the full cavity wall the rest of the house has (the wall underneath the windows is currently in keeping with the rest) and would allow me to use the room or leave it open at all times.

archtech

A solution is to locate the structural posts inside of the window envelope, ie the windows run past the structural posts on the outside.

martinn123

archtech wrote: »

A solution is to locate the structural posts inside of the window envelope, ie the windows run past the structural posts on the outside.

Yes,
there are a couple of systems which use a portal frame.
So the ridge detail, in steel, is carried down to a frame, which sits on the foundations in the inner leaf.
When fitted the outer leaf, is then laid, and the windows will sit on the outer.

with regard to,

fclauson wrote:

You might want to put the challenge to the window suppliers - how do you get a thermally efficient conservatory

this is a problem with a Conservatory as its a glass bubble, but this query relates to a Sunroom, so a solid roof. Glass technology has come a long way, but not to match a fully insulated solid roof, ( we are trying )

Mellor

ShiverinEskimo wrote: »

But that would mean leaving it closed off during times the house is being heated in the winter. As it is it's kind of doubling up as a bit of a living/dining area off the kitchen so I don't think it's feasible or practical for me to keep exclusive from the main house.

Well the point close it off and not waste energy when not using it. Or open up the large doors when you are.

The blocks replacing the posts would allow me to wrap the windows with the full cavity wall the rest of the house has (the wall underneath the windows is currently in keeping with the rest) and would allow me to use the room or leave it open at all times.

Block posts, and the associated insulation will help but it won't make the space well insulated all of a sudden.

ShiverinEskimo

I get that the more windows and seams around windows the more heat loss there's likely to be. But seperating the windows with a cavity block wall and taping the frames etc. as in keeping with everywhere else would go a long way and would certainly be better than the existing steel posts and keeping the doors closed at all times while heating the house no?

I want a full usuable room - there's a chimney for a room-sealed stove going in too - so if i'm using the stove I don't want to be heating the earth while i'm at it.