Anyone done DIY underpinning?

Doozergirl

The structural engineer is the absolute key. They have the qualification and the insurance to back up their calculations. Building control have the qualification and the insurance to check the job is carried out correctly. If you want the job insured, that insurance comes from the structural engineer, not the man that dug the hole.

The person digging the hole likely has little or no qualification to keep a house standing (no offence intended but if the integrity of my home lay with the bloke that dug the holes on our first underpinning job, I'd never have moved into it). It's in getting the calculations right. Even the width of the holes is set to keep the person digging safe.

No insurance company, nor building control check the credentials of the person digging.

No-one has suggested, not even the OP, that he attempt to do the calcs himself. If, to the person doing the physical work, it isn't digging holes to the correct specification, filling the holes with the correct amount of concrete and then backfilling it, what is it exactly?

Bungarm2001

Structural engineer is coming around next week. He has quoted what I think is a very reasonable price for a comprehensive set of calculations, drawings etc etc. When my son mentioned to him he may be tackling the job himself, the SE didn't bat an eyelid. No doubt he'll be giving him plenty of advice when he turns up to measure up the job.

We will definitely ask to see some sort of insurance for the calcs. Who knows, he may well tell him to get a builder in and refuse to work with an amateur. We'll wait and see.

We are well aware that if the BI isn't happy with the job it'll probly need rectifying before getting signed off and this will likely cost a packet. As the whole object of the thing is to save money, he is hardly going to put himself in that position by being cavalier about the whole thing.

We (the parents) have been renovating properties for years so working with a BI and knowing what they want is almost second nature now. We are also well and truly aware that it isn't just a matter of digging a few holes and chucking a few barrow loads of concrete in, this is why I am asking for othwer peoples' experiences with this.

Please believe me, I truly do understand where you guys are coming from re people not being willing to pay the going rate for a job well done. On the other side of the coin, you have to realise that sometimes, people are between a rock and a hard place. Money is very tight and they desparately need another bedroom and this is the only way they are going to get it. They have very little money that is going to have to stretch a very very long way.

Canucklehead

ukwoody wrote: »

By the way, Phil I had a similar rant a little while ago about peoples perspective of tradesmen and the rates we charge

Good morning: The 'Ranters' Club is getting larger by the day..welcome to the fellowship;) I've lost count of the number of tirades I've had on this forum over the years (I'm usually the polite Canadian) but it needs to be said from time to time. BTW, while I'm at it, my other pet peeves include MSErs who are unfamilar with the use of the 'thanks' button/the word 'thanks' and posters who don't update/respond despite getting oodles of assistance from the tradespersons and experienced DIYers who post in response.

HTH

Canucklehead

nelly_2

Underpinning is one of them things that has an auror around it that scares most people, or that its super scientific and that.

When the reality is - digging a hole and bunging a load of concrete in it.

It does'nt need loads of serious calculations <

---

they are for doing things to a minimum requirement.

I just pulled a wall out of my house and not bothering with building regs cos the steel I am putting in is well over the top, I'm putting two in instead of one and building a new meter wide wall to carry it.

Overkill is okay its underkill that might....erm....kill you

richardw

richardw wrote: »

Check the insurance premium costs and what the mortgage conditions might say and the building insurance policy.

Any thoughts?

Steve_xx

richardw wrote: »

Any thoughts?

Once the property is underpinned the OP will have one hell of a job getting buildings insurance, and oddly enough, they may/will face some difficulty in obtaining contents insurance too. I'm not entorely sure why that is; perhaps if the house fell down and the contents were destroyed in the process........?

Most insurers will not want to know about it and those that do will normally want to send out their surveyor and there will be a helfy charge for this. The premium will be hiked because they will assume that there is some risk as it's been underpinned, or even worse, they may decline to honour any claims for heave or subsidence at the property.

You will have to declare to your insurer that it has been underpinned.

Doozergirl

What? The OP's son is building a second floor extension. The original foundations only needed to hold one storey, now they need to hold two, hence they need underpinning. It's logical sense. Just because they are underpinning it to build an extension does not mean the house is falling down!

I know I'm arguing with people over whether the guy should dig the hole, but saying that you won't get buildings insurance because you've increased the foundations to add another is just uneducated madness. You may have issues if your house is suffering from subsidence, but this house is not.

There really is such a stigma attached to the word 'underpin' that people really do think it's some really scary complicated thing. It's not. Underpinning is a solution, not a problem in itself.

rdpro

I can see the point if they fill in the hole with sand..

Structurally speaking, there must be a mix that's approved for this?

Steve_xx

Doozergirl wrote: »

What? The OP's son is building a second floor extension. The original foundations only needed to hold one storey, now they need to hold two, hence they need underpinning. It's logical sense. Just because they are underpinning it to build an extension does not mean the house is falling down!

I know I'm arguing with people over whether the guy should dig the hole, but saying that you won't get buildings insurance because you've increased the foundations to add another is just uneducated madness. You may have issues if your house is suffering from subsidence, but this house is not.

There really is such a stigma attached to the word 'underpin' that people really do think it's some really scary complicated thing. It's not. Underpinning is a solution, not a problem in itself.

I can assure you that the mention of the word "underpinning" to an insurer will present a problem in obtaining insurance. With reference to your comment "uneducated madness" I would inform you that I have personal experience of underpinning and I reiterate the fact that once mentioned to an insurer that there will be difficulty in obtaining cover.

I agree that underpinning is a solution rather than a problem. However, to a potential insurer an underpinned property is indicative that there has been a problem and therefore there may be an increased risk. Insurers do not like risk.

Doozergirl

If you knocked down the entire 19 year old extension, complete with it's insulated cavity walls, broke up all it's existing foundations, carried them all away and then dug a nice new hole and poured some nice new concrete in, built another almost identical cavity wall in it's place but taller, could I avoid insurance problems then? :wall: It's perfecly normal to strengthen existing foundations to carry a heavier load, like it is normal to replace the existing joists in the loft for bigger ones to distribute the new weight of a loft conversion. It's just that the new job is different to the one they were designed for originally. It doesn't mean they are inadequate for the job they currently do.

If you have subsidence or heave, that is an issue. Insurers will sit up and take notice of those words because there maybe a potential issue with moving ground that may reoccur. The ground underneath the property is not going to move any more than it might have done once the foundations are strengthened correctly to take the weight of the new extension. Underpinning in these circumstances is not an issue for insurers, it just saves knocking the whole house down to create new foundations.