Building a bungalow with attic extension in mind

MegamanBoo

I'm looking at starting the process of building a house. With costs as they are, as well as just trying to be sensible, is it practical to design a small, simple rectangular bungalow with a view that the attic could be easily converted in future?

Taking say a simple 100 sqm fully rectangular bungalow the questions I'd have would be:

What would be the implications cost wise for the initial design and build, to make it attic friendly in future?

What % of the attic space could be used in future, from the look I've had there are additional requirements if going over 50 sqm attic in terms of building regs.

Would it change the approach in how to meet a2 (or is it a1 now?) ber requirement.

Any help, or suggestions greatly appreciated.

seamus

The biggest issues people encounter with attic conversions are access, roof height, and truss support.

If you plan from the start to have a space where you could fit a full-size stairs for a conversion, a tall roof giving you a decent space with 2.4m head height and the appropriate roof supports and joists, then it shouldn't add a considerable amount to the actual build. Any later attic conversion will then involve just adding the stairs, Velux windows, flooring and panelling.

gctest50

You'd get a lot more useable room with this kinda roof


https://imgur.com/DdWnlE7

Biker1

seamus wrote: »

The biggest issues people encounter with attic conversions are access, roof height, and truss support.

If you plan from the start to have a space where you could fit a full-size stairs for a conversion, a tall roof giving you a decent space with 2.4m head height and the appropriate roof supports and joists, then it shouldn't add a considerable amount to the actual build. Any later attic conversion will then involve just adding the stairs, Velux windows, flooring and panelling.

All of the above plus a plan for airtightness and insulation.

Calahonda52

The key one is decent floor joists, so 9 by 2 or so.
Plan where the stairs will be and put in 9 by 3 for the opening..
Plan where any velux windows will be and put the rafters at the right spacing, doubled up
Converting after the fact is a bitch so I would get the slope sorted with insulation, membranes etc and run the wires from the board as well as any other ones.
Then insulate the flat ceiling so as the heated space is downstairs.

dzer2

When applying for planning include the conversion at the start then you will have no problems later.

Design It as a dormer from the start.
Leave the roof area the right size and headroom.
You will.need to put in the support timber from end to end both sides. Make sure.water tank is up on the top. Design the first floor/ceiling with a stairs in mind. Put in the openings for the formers and velux if you intent on having them. You can have one window in the attic with planning. Put in room vents in walls. Rout wiring and water so you don't have to alter later

Hope this helps

LV-426

Presumably your future stairs will be in the hall from front door so make sure hall can accommodate stairs. Could put in the roof windows at initial build stage and also floor attic with ply at the start as well. Put in attic stairs at the start and have great storage/gym space although it is a pain cleaning everything out when the actual conversion happens.

LV-426

Yes put water tank in correct place from the start

LV-426

Rafters will need to be big enough to accommodate right size insulation and leave enough gap for ventilation.

MegamanBoo

Calahonda52 wrote: »

The key one is decent floor joists, so 9 by 2 or so.
Plan where the stairs will be and put in 9 by 3 for the opening..
Plan where any velux windows will be and put the rafters at the right spacing, doubled up
Converting after the fact is a bitch so I would get the slope sorted with insulation, membranes etc and run the wires from the board as well as any other ones.
Then insulate the flat ceiling so as the heated space is downstairs.

Roughly speaking will it add much to the cost to insulate the slope straight off?

I'm not up on what roof insulation would look like otherwise in a bungalow with the newer A rating requirements. Would it be 12" rockwool with a membrane still under the joists?

MegamanBoo

LV-426 wrote: »

Yes put water tank in correct place from the start

Is that right under the apex of the roof in a dormer? Excuse the ignorance!

LV-426

MegamanBoo wrote: »

Is that right under the apex of the roof in a dormer? Excuse the ignorance!

In the eaves I would say

MegamanBoo

dzer2 wrote: »

You can have one window in the attic with planning. Put in room vents in walls.

Is that one window without planning?

By room vents in walls do you mean gable walls so I'd have ventilation in the dormer part?

Calahonda52

MegamanBoo wrote: »

Is that one window without planning?

By room vents in walls do you mean gable walls so I'd have ventilation in the dormer part?

That window point is not correct.
The insulation can be added over the rafters.
Go MHVr and forget about wall vents

dzer2

MegamanBoo wrote: »

Is that right under the apex of the roof in a dormer? Excuse the ignorance!

If you have no bathroom or shower upstairs the eaves would fo but to be safe right under the eave will give room for modifications. Also make sure the sewage from upstairs has an out the vent pipe is normally used

BryanF

MegamanBoo wrote: »

Roughly speaking will it add much to the cost to insulate the slope straight off?

I'm not up on what roof insulation would look like otherwise in a bungalow with the newer A rating requirements. Would it be 12" rockwool with a membrane still under the joists?

That’s the thing. You need to seal and insulate the house you want to heat. But plan all the details for future conversion. With dormer conversions, not many get the air-tightness and insulation continuity right.