Rear extension to double bay property

Walshy252

Hi all

Hoping for some advice here as I have conflicting information from two builders. We are waiting for a quote from a 3rd but even so I don't think it will solve matters.

We are in the process of purchasing (surveys this week) a 1950s semi detached house with double bays. We liked the rear bay windows as it increases the space in the rear bedroom by some way. Our aspiration is to extend the dining room which also has a bay window, by c. 3x3m to make a bigger kitchen diner. I have attached the current and proposed floor plans (not fully scaled and sketched by me for illustrative purposes only).

Builder 1 says that it is doable for £20k and needs a couple of RSJs to support the wall. This included costs for bi fold doors to the rear and pitched roof with skylight

Builder 2 has quoted £23k and says that this includes removal of the upstairs bay and replacement window, as it is no longer supported if the downstairs bay is removed. He also wants to keep some sort of supporting pillars between dining room and kitchen where the wall currently stands.

Of course we could get an architect out however at this stage we are more interested in whether it is possible to remove the downstairs bay and extend without compromising the upstairs bay window and associated space in the bedroom. We are also trying to budget for other improvements so a good idea of what is achievable and for how much would allow us to go out and engage an architect once we have completed the purchase.

Many thanks

Original plan
Tinypic.com/r/e622bp/9

Proposed plan
Tinypic.com/r/iwoh1j/9

FreeBear

Doable, yes. But the floor plans would seen to suggest that there is already one RSJ in the middle of the kitchen, To remove the wall as indicated in your proposed plan would mean some serious steelwork installed and I think the original RSJ would need to be replaced.

I have my doubts as to whether a £20K budget is realistic...

Doozergirl

Have they quoted based on the floorplans you've just shown us? With a comment attached that you could keep pillars in 'if required'.

At the moment it looks like you're relying on levitation to hold the back of the house up.

I'm astounded that anyone would even consider quoting without the structural engineer's assessment.

Builder 1 is certifiably insane, bold
And capital letters. Builder 2 is much closer but I would not *dream* of giving someone a price without a solid plan of how the house is. held up.

I seriously question the pricing as well. This isn't just an extension, it's a serious smash up of almost the entire downstairs with the entailing a huge amount of piecing back together.

This needs planning properly with serious consideration of the layout of the final room, including its structural limitations and knock on effects to the electrics and plumbing if you only have £20k.

What's your kitchen budget?

bay does create awkwardness, but no more than the rest of your expectations.

Walshy252

Have they quoted based on the floorplans you've just shown us? With a comment attached that you could keep pillars in 'if required'.

At the moment it looks like you're relying on levitation to hold the back of the house up.

I'm astounded that anyone would even consider quoting without the structural engineer's assessment.

Builder 1 is certifiably insane, bold
And capital letters. Builder 2 is much closer but I would not *dream* of giving someone a price without a solid plan of how the house is. held up.

I seriously question the pricing as well. This isn't just an extension, it's a serious smash up of almost the entire downstairs with the entailing a huge amount of piecing back together.

This needs planning properly with serious consideration of the layout of the final room, including its structural limitations and knock on effects to the electrics and plumbing if you only have £20k.

What's your kitchen budget?

bay does create awkwardness, but no more than the rest of your expectations.

Both have quoted based on the floor plans shown, though B2 advised it is subject to change once he views the property (fair enough). We budgeted another £8k for kitchen refit on top of the extension and we removal and expected this to include some additional strengthening work.

To my knowledge the kitchen is the original building rather than an extension, as the other houses in the street have similar layouts. Therefore not sure whether any RSJS are in place as yet. Since we haven't bought the house yet, we sketched the plans to determine if the work was feasible and to get a rough idea of cost. Naturally we expected this to be a ball park figure given no SE assessment.

On moving in we may decide that simply removing the wall and making the existing space more open plan will be sufficient. Though we really wanted to extend as well to make the most of space and light

martinsurrey

6-8 steels required for that floor plan (inc retaining the upstairs bay), maybe more, depending on wall strength and foundations, worst case is around 12 steels needed!

£20k is pie in the sky, or seriously skimping on structural elements!

and that's without considering drainage and electrics as mentioned by Doozer.

I would be getting a Structural engineer to design, and then get quotes after that.

Doozergirl

There will be an RSJ across the kitchen. I very much doubt that it is original, but if it is, that doesn't stop there from being a structural wall spanning across it. It needs holding up and that can only be done in one place and that will be the same as if it were an extension.

Open up the full back wall and the kitchen and you're going to have one impossibly heavy steel with another two locked into it.

The bay does provide a challenge, moreso when you want two entire walls removing.

Builder one doesn't appear to have a brain cell in his head. Whilst not qualified to calculate, any 'builder' should be able to understand how a house continues to stand up. I highly recommend never speaking to him again.

Builder two has avoided the engineering issues by leaving in the pier and removing the bay. If you want more than that then expect the price to rise exponentially.

You'll maybe gain some room from the hall into the kitchen if you open plan the existing and move the door further into the hallway.

System

Anything is possible, the only variant is the budget!
IMO you don't have the budget for this kind of radical alteration with structural gymnastics