Extension over Garage

Question

We are thinking of extending over our garage but given the scale and price of the work is it possible to do in phases?

We live in a semidetached linked by garages house.
The Garage is sloped currently. Very high at front and low at the back.

I think it would be more achievable to the following
Get planning/building regs.
Check or modify the footings
Raise the back end to a standard height
Lower the front end to a standard height
Rubber roof

Then do the 2nd floor at a later date for phase 2?

Nicholas · Accepted Answer

Yes, a phased approach is possible, but there are a few key factors to consider:

Phase 1 – Preparing the Garage for Future Extension
	1.	Planning & Building Regulations – Get approval for the full two-story extension upfront to ensure Phase 1 is built with Phase 2 in mind.
	2.	Footings & Structural Work – The foundation must be strong enough to support a second floor later. If the existing footings aren’t deep enough, they’ll need reinforcing now.
	3.	Adjusting Garage Height – Raising the back and lowering the front to create a level structure makes sense and should be done before roofing.
	4.	Roofing Choice – A rubber roof is a good temporary solution, but ensure it’s designed to be easily removed or modified for the second-story extension.

Phase 2 – Building the Second Floor
	•	Once Phase 1 is complete and you’re ready for Phase 2, the second floor can be built with minimal disruption, provided the groundwork has been properly set up.

Key Considerations
	•	Cost efficiency – Some builders may charge more for a phased approach than doing it all at once due to extra labor and material adjustments.
	•	Weatherproofing – Ensure the Phase 1 roof is properly sealed to prevent issues when removing it later.
	•	Structural continuity – The walls and load-bearing elements must be designed with the second story in mind to avoid costly modifications later.

Would you be keeping the garage functional during Phase 1, or are you planning to convert it into a living space eventually?

Rebel · Answer

First of all you have to identify if your garage was built on a single storey foundation or a two storey foundation then you can proceed to plan the extension

Josh · Answer

You absoloutley could do this. The only problem is that you will have a much higher cost in the long run .

Phases are usually done like this .

1. Foundations 
2. Build to roof plate 
3. Roof 
4. Windows and doors 
5. Electrics & plumbing
5. Knock through & plasterwork

Doug · Answer

First things first are the footings of the garage  capable of  taking a second floor 
This would dramatically effect the cost of the project

Billy · Answer

That is more achievable and you could get a price for both phases. Once you have planning,

Mason · Answer

Yes, it’s definitely possible to do an extension in phases, and your plan sounds like a reasonable way to approach a large project in stages. Here's how it could work:

Phase 1: Prepare the Garage
Planning & Building Regs: First, get planning permission and building regulations approval for both phases. This is essential, as any future works need to be covered under the original approval.
Check/Modify Footings: You’ll need to confirm whether the garage footings are strong enough to support a second storey. A structural engineer can assess this, and you might need to reinforce them if they’re not up to standard.
Level the Garage: Raising the back end and lowering the front to standard height can be done with underpinning or re-leveling the existing structure. The idea here is to make the garage level and stable enough to handle the weight of the second storey later.
Rubber Roof: Installing a flat rubber roof makes sense now to cover the garage and make the structure weather-tight. A solid roof is essential for the integrity of the building as you progress.
Phase 2: Add the Second Floor
Once the garage is structurally sound and leveled, you can proceed with adding the second floor at a later date. At this point, the groundwork for the foundation and the roof would already be in place.
You’ll still need to ensure that the upper structure is adequately supported by the foundations and any load-bearing walls.
Considerations for Phasing:
Cost: Breaking the work into phases will allow you to spread the cost over time, but make sure to budget for both stages.
Building Regulations: Even though you’re phasing the work, the overall project needs to comply with all regulations from the start. You’ll need to ensure that any changes made in Phase 1 are adequate to support Phase 2.
Disruption: Completing the work in phases could reduce the immediate disruption but keep in mind that there will still be long-term work to do, so plan around this.

Rick · Answer

You may not get planning approval if the work is on the boundary, check with local authority first.

Shaun · Answer

Can definitely be done although more costly with the temporary roof and the hire of scaffold for two phases

Extension over Garage

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