Anyone done DIY underpinning?

Bungarm2001

Probably not the right place to ask this, but here goes.

My younger son wants to extend his 30's semi over the kitchen extension which was built approx 19 years ago. On the advice of an architect, he dug beside the extension wall right down to reveal the extent of the footings, then called out the local BI to have a look.

The BI told him it would need underpinning to take the weight (as we suspected) and he would have to go down approx another 50mm below the existing footings. He also advised getting a structural engineer to give proper measurements etc.

He has had various quotes for doing the underpinning i.e. digging the holes (11 in all apparently) and taking away the waste, doing the concrete fill etc and the cost has varied between £4,550 to £6,000

Now my question is, as it is basically digging a series of holes then filling with concrete, has anyone ever ventured to do this themselves? If so, would you share the experience/any advice etc? Obviously he will be getting as much advice as possible before starting, so I thought I'd ask on here on his behalf...many thanks!

macduf

You dont say the overall size of the Extension. and how far you are going to have to dig down.
Judging by the Quote of £4,550 I would assume its not a Large Extension and that you are not digging down that far. Its very Likely you will find that the Structural Engineer will want Steel Rods putting in so I think you may find the Quotes you have had will increase upon his report.
You could undertake the work and would save Money but its not an easy Job.

withabix

I assume you meant 50cm deeper, not 50mm deeper, as the latter would be fairly pointless.

Structural design calculations will be required for the underpinning, which will be required by any future buyer's solicitor when you come to sell. You will also have to satisfy your local authority's Building Control that the work was carried out properly.

Please leave this work to someone who knows what they are doing. From a health & safety point of view and also in terms of insurance if things go wrong. If you go about underpinning the wrong way, your kitchen will fall down.

This is NOT a job for a DIYer.

Personally I would do this work myself, but then I am a qualified Civil Engineer and deal with much more complex design and construction issues every day.

ukwoody

I wouldn't touch it. If there are problems later you want have a leg to stand on with the insurance company.
This is another of those tasks should be left to a pro in that field.

woody

phill99

ukwoody wrote: »

I wouldn't touch it. If there are problems later you want have a leg to stand on with the insurance company.
This is another of those tasks should be left to a pro in that field.

woody

Woody is absolutely right. Don't touch it as you could be opening a huge can of worms. I know this forum is about saving money and getting value for money, but underpinning your own house isn't one of them.

I'm new to this forum and run my own Maintenance Company, but I wouldn't take underpinning on. Its only for the pros.

On that note, there seems to be a lot of people on here that seem to think that all tradesmen are trying to rip them off. There are rogues as seen on Rogue Traders etc, but most tradesmen aren't. There are rogues in all professions and occupations. Most tradesmen just want to get on with their jobs and do a decent job because their reputations are staked on it. And this constant quest to push prices down all the time does no body any good at all. There is no justification to overprice a job, but customers constantly pushing prices down just results in contractors having to cut corners. Customers think that a tradesmand day rate is all that should be charged omn a job. But it costs me over £150 per week just to run the business ie accountants fees, insurances, vans, admin costs etc and this has to be factored into prices.

Sorry to highjack youir thread, but this needs to be brought to peoples attention.

real1314

I paid £5k for the foundations for my 3m x 5m 2 storey extension, due to needing piling. But that £5k includes a full guarantee, structural assesment, and ensured that building regs were passed without question.

Not worth skimping on imho. There are thing that you can DIY and there are things that aren't worth considering.

Doozergirl

If you did do it yourself, you could get all the appriopriate drawings and specifications from a structural engineer and support from your building inspector who needs to come out and check the holes anyhow. I would continually ask questions and have people check what you are doing constantly.

It is essentially digging hole to a certain size and filling it with concrete though you obviously need to have all your measurements correct. The first time we had it done it was all done by a contractor. It didn't come with an insurance policy from the contractor. You just need the relevant sign offs from building control and then you are covered by your own insurance and the structural engineer's insurance if he got the calcs wrong. Building control check that you've dug your hole correctly to the calcs.

It's REALLY hard work though. Even my H gets someone else to dig! It's really dirty, hard work - that's why it's so expensive I think, more than being complicated

Canucklehead

phill99 wrote: »

Woody is absolutely right. Don't touch it as you could be opening a huge can of worms. I know this forum is about saving money and getting value for money, but underpinning your own house isn't one of them.

I'm new to this forum and run my own Maintenance Company, but I wouldn't take underpinning on. Its only for the pros.

On that note, there seems to be a lot of people on here that seem to think that all tradesmen are trying to rip them off. There are rogues as seen on Rogue Traders etc, but most tradesmen aren't. There are rogues in all professions and occupations. Most tradesmen just want to get on with their jobs and do a decent job because their reputations are staked on it. And this constant quest to push prices down all the time does no body any good at all. There is no justification to overprice a job, but customers constantly pushing prices down just results in contractors having to cut corners. Customers think that a tradesmand day rate is all that should be charged omn a job. But it costs me over £150 per week just to run the business ie accountants fees, insurances, vans, admin costs etc and this has to be factored into prices.

Sorry to highjack youir thread, but this needs to be brought to peoples attention.

Good afternoon: I agree 100%...my OH is constantly 'nickel and dimed' by individuals who want the cheapest job possible,and have 'to hell with Building Regs' attitudes....he doesn't work for these type of people as a consequence of his ethics and professional standards...fortunately there are customers out there who appreciate the skills of a qualified tradesperson. BTW, we would call in the professionals for underpinning despite my OH's 30+ years in the building industry...know your limitations;) My apologies to the OP also.

HTH

Canucklehead

Bungarm2001

Thanks doozergirl...I agree with everything you say..!:D

Just to clarify...the 50mm was a typo..sorry The BI told us that the footings in total would have to be 750mm to get down to the 'white' clay; the inspection hole has revealed 450mm existing footings depth so I don't know where I got that figure from! (brain fart I think!)

The whole existing single story extension is 3m x 5m.

One of the neighbours digs holes for underpinning for a living, so he is more than happy to 'hold his hand' through the whole job. He is also going to lend any 'toys' (his word, not mine!) that he might need to make life easier.

The neighbour immediately to the right is in the process of doing a huge wraparound extension and is doing ALL of it himself. He also works in the local planning office and is also more than willing to help out with drawings, plans submission etc and is going to help where he can. Also, the BI's are friends of his, so my son has plenty of help in all the right places.

Before he does anything tho, he has booked a strutural engineer who has promised a full set of calcs, measurements etc including weight of the new roof and anything else he can think of between now and when he turns up. I will get him to mention insurance tho...a good point, thanks!

I take on board all you guys have said about using a qualified experienced builder, and he will do when it comes to things that he really can't tackle, like the roof, bricking up the walls etc, but digging holes, no matter how big or difficult is still that..digging holes and rightly or wrongly, he really can't justify the thousands of ££'s costs involved.

Thanks for all the advice guys..it really is appreciated..! :beer: :beer:

richardw

The BI's may be friendly but if it isn't done correctly he won't get a certificate and will have to get it sorted out which may cost. Check the insurance premium costs and what the mortgage conditions might say and the building insurance policy.

It isn't as simple as digging and chucking concrete down the hole.

ukwoody

It is NOT just a case of digging holes and filling with concrete.
Like Phil99 I run my own property maintence company, have Advanced City and Guilds, nearly 30 years extensive experience, have been the Building maintenace supervisor for an extremly large NHS Trust covering 4 sites, Overseen the £2M rebuilding of a fire damged school... and still wouldn't dream of undertaking that kind of work. It is a can of worms.
I'm sorry if this sounds rude, but what is the point of asking tradesmen, when at least 3 of us say NO, then ignoring the advice you are given?

By the way, Phil I had a similar rant a little while ago about peoples perspective of tradesmen and the rates we charge. MY van does just 24 miles to the gallon, my lowest paid employee gets £50 per day. I charge him out at £100. Why? by the time you've paid employers liablilty, Public liability, the con that is called N.I where I pay more than he does, his holidays, sickness, and cockups, pick him up an drop him off, I reckon I just about break even on that!
For me to earn a wage of just £250 per week gross, I have to bring in £1800 per month, to cover the van costs (tax, mot, servicing, wear and tear insurence, diesel), workshop rental costs (and water, council rates, electric), insurences, tool wear.

Sorry, rant over! :-)

woody