Chalet Bungalow- extension onto already extended single storey side/rear extension

[iona mackenzie]

I am hoping you can all give me a little help. 

 

We have a chalet style bungalow with dormer on both sides. The previous owners added a  3m single storey extension with a flat roof (Kitchen) to back of the bungalow along with a side extension (3.25m)

 

We are looking to further extend the kitchen by 2m, while also building 2nd storey(1st floor) onto the the already there flat roof, (extend out of the dormer,) to add a 3rd bedroom upstairs and to make existing bedroom slightly bigger, while also reducing to only 2 bedrooms. 

 

From the drawings attached we are sure that the foundations on the existing extension are suitable. 

 

SO my question is.... has anyone done this before?

Can we build onto the flat roof? 

Can you extend out of a dormer?

Would we have to replace the entire roof? Or maybe change it to Mansard roof? 

What's the cost of modular roofs? 

 

Any advice and ideas would be fantastic. 

 

I've attached drawings from when the previous owners extended, hopefully can make sense of them 

 

Many Thanks 

west_lane_kitchen_extension_2.pdf

[Temp]

Welcome to the forum. My builder liked to say you can build anything if you have enough money.

 

The dormer is quite narrow so when you say extend the dormer do you mean...

 

a) turn it into a corridor to a much wider first floor bedroom or

b) make the whole dormer wider?

 

When you extend the kitchen 2m I assume you will be removing the wall so the kitchen is two meters bigger? That and the fact you want a room above may mean sections of the flat roof ends up being replaced. 

 

This will certainly need planning involvement but I guess it might not need a full planning application. Deeper rear extensions are allowed on detached properties under the pre-approval/neighbour consultation scheme. The government is also in the process of changing the rules on adding extra floors which might help a lot. I would wait for the details of that to be published before going too much further.

 

I would see if the person that designed the original extension is still around. Find out if he can comment on the feasibility of doing what you want and quote to do the drawings.

 

 

[DevilDamo]

You would need to carry out a few structural checks of the existing structure to make sure it’s adequate to receive the additional load. Never rely on drawings as that is not always what has been built.

 

Assuming the extension is not recent, i.e. built within the last 5 years, Building Control would ask for the existing foundations to be exposed. If they’re not adequate, they may have to be underpinned. If the extended first floor element is to be constructed like a dormer so utilising timber frame, then that will obviously limit the additional applied loads to the existing foundations. Or you take the rear wall up as cavity wall but with a flat roof.

 

The existing flat roof joists would need to be checked to determine their suitability to use as floor joists as the loadings are a lot different. You’d also need to check the floor levels between the existing and new incase any small internal steps have had to be created as a result of increased first floor joist sizes. This is easily alleviated by having a slightly lower and dropped ceiling to that rear part meaning the first floors can remain flush. To hide that step down below, you’d to look to incorporate a small suspended ceiling to the existing part of the main house.

 

Depending on what structural and thermal upgrade requirements are require to the roofs will end up dictating the practicality and feasibility of modifying or replacing the existing.

 

Your starting point would be to have an architect/technologist/technician/designer round to run through the options and pro’s and con’s of the various processes and methods.