How do I find out how much/ how feasible major alterations to my property will cost?

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Really need some advice though not sure if this is the correct section of the forum to post in.

We want to reconfigure the layout of our house. The house is semi detached and on the side of a steep hill. We want to convert half of the existing basement area into a large living room This will require some structural works including the removal of load bearing walls, the installation of the required steel beams etc. plus the levelling of the floors, installation of bi-fold doors and a new staircase. There are some areas of penetrating damp which will need attention but nothing major.

How do I find out what the likely cost will be? I don't want to pay for expensive plans etc. to then discover the build cost is way more than I can afford. I have never needed to engage builders before other than for a rewire and new windows and don't know anyone who has had this kind of work carried out.

Thanks for any help you can offer.
 
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How do you expect someone to quantify costs if you don't have any plans, schedule or specification drawn up?

Some may say that the costs of any plans or specification are many times less than the additional costs of a builder guessing.
 
Need eyes on really unless you want total guesses in the dark.
Quotes first, expensive plans etc second.
 
Quotes first
What will be quoted on? A 6" or a 10" beam, a full or part build of a wall, a structural engineers validation or just a building inspector check, a Worcester or Ravanheat boiler? Etc

And how good is the person quoting? He's hardly going to itemise the quote, so they can't even be used for comparison.
 
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What will be quoted on? A 6" or a 10" beam, a full or part build of a wall, a structural engineers validation or just a building inspector check, a Worcester or Ravanheat boiler? Etc

And how good is the person quoting? He's hardly going to itemise the quote, so they can't even be used for comparison.
Yes you are correct woody, to the op, find a builder to visit and to talk with.
 
Thanks for your help guys. I knew my question would cause problems. If I take my car to a garage with a fault the professional will normally say it's likely this wrong mate and will likely cost x but we both know it's an estimate and not a solid quote until he's had a proper look. Applying this logic I assume I would try and find a reputable builder to have a look and be given a rough ball park figure which if I'm thinking 40k and he thinks more likely 60k then I can forget the idea because it's beyond my budget ( or he may have other suggestions that I can afford).
I personally don't know anyone who would spend several 1000s having plans drawn up to present to a builder to find it completely unaffordable.

What I just wanted to know, and Just Pumps has confirmed is if it is acceptable to ask a builder to have a look and use his professional judgement for me to find out if it's within my price range. Other threads on here mention engaging builders who have a network of Structural engineers/ architects they normally use who they would engage on your behalf, so plans and SE calcs would be done and firm costings only carried out and confirmed after a builder was consulted.
 
Thanks for your help guys. I knew my question would cause problems. If I take my car to a garage with a fault the professional will normally say it's likely this wrong mate and will likely cost x but we both know it's an estimate and not a solid quote until he's had a proper look. Applying this logic I assume I would try and find a reputable builder to have a look and be given a rough ball park figure which if I'm thinking 40k and he thinks more likely 60k then I can forget the idea because it's beyond my budget ( or he may have other suggestions that I can afford).
I personally don't know anyone who would spend several 1000s having plans drawn up to present to a builder to find it completely unaffordable.

What I just wanted to know, and Just Pumps has confirmed is if it is acceptable to ask a builder to have a look and use his professional judgement for me to find out if it's within my price range. Other threads on here mention engaging builders who have a network of Structural engineers/ architects they normally use who they would engage on your behalf, so plans and SE calcs would be done and firm costings only carried out and confirmed after a builder was consulted.


Is the basement currently usable space?

I guess as you want bifolds the basement is at ground level to the read garden, but the front of the house has ground level almost a story higher?

A basement below ground level that needs totally tanking and pump with float is a lot different to say a basement that might need a few £k of Cavity drainage system before plastering.


If you did some rough plan drawing with dims and a list of what you want done, it should be possible to get put some rough numbers on it. Stick it on here, I'm sure you get some indication prices.
 
Is the basement currently usable space?

I guess as you want bifolds the basement is at ground level to the read garden, but the front of the house has ground level almost a story higher?

A basement below ground level that needs totally tanking and pump with float is a lot different to say a basement that might need a few £k of Cavity drainage system before plastering.


If you did some rough plan drawing with dims and a list of what you want done, it should be possible to get put some rough numbers on it. Stick it on here, I'm sure you get some indication prices.

Hi Notch7,

Yes the basement is currently usable, was rewired along with the rest of the house shortly after moving in 3 1/2 years ago.

When the house was built in the 60's the basement level was unfinished with access only from outside. Over the years the occupier in common with all the other home owners in the road made them into habitable rooms with internal staircases etc. I have seen inside a few of my neighbours properties and they are all cobbled together amateur jobs like mine. As you can probably see in the photos ( sorry for the mess!!) the different floor levels make it a pain to use. There are a few areas where damp is coming through, mainly the front wall which is directly into the side of the hill, and a few small areas on the floors in the two main rooms. Our neighbour solved his damp issues by having the walls tanked.


Works desired:

Remove walls marked with crosses on the diagram. Installation of steel beams /lintels to provide replacement support .
Replace the stairs with open plan wooden stairs.
Level all floors which would involve the lowest floor being raised by approx 18 inches ( plenty of height in the rooms to allow for this, the room with the patio door has a false ceiling with a 24inch void.
BI fold 4.5 metre wide door leading to the back patio ( so steel lintel inserted to allow for this)
New back door to replace the old one but raised up to the correct height with new lintel for the opening ( door needed to access the conservatory we might put on the side patio)
Damp proofing works

The room next to the cupboard would not be changed apart from some damp proofing.

Hope I've provided enough information.
 
I don't know what I'm doing wrong but I've created a media album ( Basement rework) but I don't seem able to attach the pictures to my post even though they show up in preview mode......
 
Basement work especially waterproofing is highly specialised. You don't just want any old Joe giving an opinion or even a price.
 
Woody, you are obviously a well respected contributor to this forum and must know your stuff but where on here have I given the impression I will ask "any old Joe" his opinion?

I don't expect a builder to come round and have a quick look and provide me with an exact price for the job.

I want him to use his professional opinion based upon his previous experience to give me an idea whether my plans are workable and an idea of the likely costs of the build and whether he would be interested in carrying out the work once the appropriate plans/ calcs and permissions have been drawn and fully costed. An experienced builder should be able to make a reasonable estimate of the costs and work involved to at least enable me to decide if it is affordable.
The basement ( if that's the correct term for it because only the front section is below ground because the house is on a steep hill) is fully habitable and has been for many years. It had been tanked or sealed when it was originally improved probably 30-40 years ago and in a couple of places this tanking needs re-doing, we are not talking a huge amount work here.
I also would make sure I had a contingency fund to cover any unforeseen problems.
 
Woody, you are obviously a well respected contributor to this forum and must know your stuff but where on here have I given the impression I will ask "any old Joe" his opinion?

I don't expect a builder to come round and have a quick look and provide me with an exact price for the job.

I want him to use his professional opinion based upon his previous experience to give me an idea whether my plans are workable and an idea of the likely costs of the build and whether he would be interested in carrying out the work once the appropriate plans/ calcs and permissions have been drawn and fully costed. An experienced builder should be able to make a reasonable estimate of the costs and work involved to at least enable me to decide if it is affordable.
The basement ( if that's the correct term for it because only the front section is below ground because the house is on a steep hill) is fully habitable and has been for many years. It had been tanked or sealed when it was originally improved probably 30-40 years ago and in a couple of places this tanking needs re-doing, we are not talking a huge amount work here.
I also would make sure I had a contingency fund to cover any unforeseen problems.
There was mention of getting quotes from a builder, and letting a builder have a look.

Now, lots of builders would love to have a look and give quotes, but very few of them will actually know what to do in a basement. Some will mention tanking without actually knowing what it is or what products are available, some won't know what regulations apply, and some may have a bit of a clue. A specialist tanking contractor won't be good at other work.

But all will probably give you one price or another, thousands of pounds apart and you won't ever know what they are actually quoting to do, what products they will fit and how the work will be carried out.

That's why you don't let any old Joe, or any builder come and quote. You'll just get random meaningless figures.

You get the design and specification produced first then every Joe quotes on that, they quote on exactly the same things, same materials fitted in the same way. Then the only difference is their price and their time to build, and you can compare every single quote like for like.
 

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