Worries about a large extension on house

50Twuncle

We are looking in to getting a large extension on the side of our house - comprising a downstairs bedroom with wet room off it and a kitchen extension behind it.

I am concerned about the actual work (a kitchen extension to the side of the house) - I take it that the new extension and roof will be constructed before the wall is removed (and presumably RSJ'd)

Otherwise - what is to stop unwanted visitors (and weather) from entering the property ?

Also - I want a pitched roof - is this normal for such extensions - I don't trust flat roofs !

JGB1955

Presumably you are employing (at least) an architectural technician to draw up the plans.  If you want a pitched roof, put that in the plans, if you want a goldfish pond in the middle of the kitchen - put that in the plans.  Builders will/should follow the plans.  YOU are the lead on this.  Tell them what you want.  Talk to them about your concerns.  They do this all of the time.  Relax!

DevilDamo

From a build point of view, they would normally build it up out of the ground and get it watertight before any knock throughs are done.

There may be some Planning or design restrictions that will dictate the design of the roof. What’s wrong with flat roofs and please don’t compare them to shed or garage roofs? There are many modern flat roof methods nowadays along with long warranties. Due to the size of some extensions, it’s quite difficult to not incorporate some element of flat roof.

Doozergirl

DevilDamo said:

From a build point of view, they would normally build it up out of the ground and get it watertight before any knock throughs are done.

There may be some Planning or design restrictions that will dictate the design of the roof. What’s wrong with flat roofs and please don’t compare them to shed or garage roofs? There are many modern flat roof methods nowadays along with long warranties. Due to the size of some extensions, it’s quite difficult to not incorporate some element of flat roof.

All of this.  

50Twuncle

DevilDamo said:

From a build point of view, they would normally build it up out of the ground and get it watertight before any knock throughs are done.

There may be some Planning or design restrictions that will dictate the design of the roof. What’s wrong with flat roofs and please don’t compare them to shed or garage roofs? There are many modern flat roof methods nowadays along with long warranties. Due to the size of some extensions, it’s quite difficult to not incorporate some element of flat roof.

Maybe I am wrong - but I have heard stories of flat roofs leaking - in any case, I feel that a pitched/tiled roof would look better - less of a lean-too /addition to the house - since the extension will be brick built - I really prefer a tiled roof !

What would be the likely extra cost compared to a flat roof ?

The size of the extension will be approx 30 feet long by 10-12 feet wide !

We had an architect out a couple of weeks ago and have a rough cost of around £35k for the shell -but don't know what sort of roof that was for.............

DevilDamo

Flat roofs leak if they’re not constructed properly but so would pitch roofs. It’s all to do with the quality of the workmanship. There is a well known wealthy estate near to me and the majority of the properties there have flat roofs and they wouldn’t do if they all leaked.

victor2

Your architect will/should know, but there is a minimum angle for tiled roofs. If there are windows in the wall above the extension roof, you may not have enough height to fit a pitched roof in. We had that problem with a 4 metre deep extension we had built and ended up with a combination of flat and pitched roof.

DevilDamo

I’d never specify anything less than 15 degrees and which is also the minimum angle for Velux’s (other brands are available...).

Although there is also the option of cutting the roof around the first floor windows (where the roof angle does come up close to the cills), it’s not in my opinion an attractive detail.

scottishblondie

As has been said the position of your first floor windows will play a major part in the roof design of a ground floor extension. Our property has a large extension built by the previous owners, complete with a “pitched” tiled roof which leaks like a sieve. We’re having to replace it with a zinc roof as the pitch is only about 7 degrees due to the upstairs windows, and there isn’t a tile in the world which is suitable for that. 

theonlywayisup

scottishblondie said:

As has been said the position of your first floor windows will play a major part in the roof design of a ground floor extension. Our property has a large extension built by the previous owners, complete with a “pitched” tiled roof which leaks like a sieve. We’re having to replace it with a zinc roof as the pitch is only about 7 degrees due to the upstairs windows, and there isn’t a tile in the world which is suitable for that. 

OT have you looked at Britmet?  Their 'lite' slate is from 5 degrees and having seen it in the flesh on a new build (in a garden) it looks rather good.  It isn't cheap though.