upcoming extension advice

[mattu27]

Hello all,
Hoping to get some advice on a few building questions before the new work starts. We are extending above our single brick garage (with double brick piers every 2.4ish M)

In order to create the 100mm cavity above we need to build out the existing piers to support an 8M long 203 X 102mm UB.

Are wall starters sufficient enough to secure the new blockwork (starting off the "to be exposed" footings) to the piers or does the new need to be somehow bonded to the existing?

And will standard 7n dense concrete blocks be the right thing to use above ground if rows of blues are first laid off the exposed footings?

Thanks, Matt

 

[Leofric]

Any plans drawn or building regulations application made

 

[mattu27]

Yep, full plans gone through all the rigmarole of it with planning permission.
BCO assigned and structural calcs aswell but they don't mention how the piers are to be reinforced.

Thanks

 

[mattu27]

Replied twice by mistake

 

[Leofric]

Yep, full plans gone through all the rigmarole of it with planning permission.
BCO assigned and structural calcs aswell but they don't mention how the piers are to be reinforced.

Planning approved drawings don't show building regulations information of course. Are you doing the work under a abuilding Notice BCO will not tell you how to build it - who is making the decisions on the building construction If structural calcs done can't your structural engineer advise on the structural aspects including the piers. There is more to bldg. regs than structural considerations of course.

 

[mattu27]

Ok,

Work is going to commence under a building notice and will be checked by our BCO along the way.

Structural calcs detail roof construction, steel sizes and positions etc. We have asked a few questions to the structural engineer but not tried again as it seems to take an age for an email reply which is why I'm asking here..

If anyone can help to answer the initial questions it would be appreciated greatly.

Thanks.

 

[mattu27]

Any help regarding this would be appreciated

 

[^woody^]

You can't normally tie piers supporting beams with vertical wall starters.

What do the engineers calcs say, that's what you need to do, as the engineer is guaranteeing the design.

For the block and brick question, you could do that, but you don't seem to have a plan, you can't make it up as you go. Building inspectors are not there to tell you how to build and may hate lots of questions

 

[mattu27]

Thanks again woody,

What would be the best method of securing the new blockwork onto the old brickwork for the piers?
Or could we instead bolt 100mm box section stood upright or similar to the piers and support off that?

I've just looked through the calcs again, the only thing mentioning supporting the steels was statement 10

But I think that's just a generic statement covering all bases and the bulk of the document is the beam calculations and internal roof design. From what's been suggested I think we need to speak with him about the construction as he should have included it in the documents.

I can see what you're saying about a plan. We aren't in the building trade and I haven't asked the builders to detail the exact construction as I don't want to come across as clueless. We have a plan so to speak but as I've agreed to get all materials I don't want to miss anything off or order anything unnecessary.

Ideally we don't want to ask building control anything about the construction as the builders have used them numerous times and seem to have a good relationship with them.

Thanks, Matt

 

[mattu27]

Hello again, can anyone shed some light on the two questions from my previous post? Thanks

 

[^woody^]

It depends how (if) the engineer has calculated the load transfer from these piers.

Normally loads are shared between the pier and the wall it is attached to, so it's either bonded in, or thicker ties built in. Wall starters don't perform in this way, and are designed to allow vertical movement so are the wrong solution.

Sometimes piers are large enough to take the loads on their own, with just some nominal support off the existing wall, so different lighter duty ties may be suitable.

But you won't know unless the engineer tells you how he has worked it out.

 

[mattu27]

Thanks again woody.

We've just sent an email over to the engineer so hopefully we'll get the details we need in a few days.

Agree, that makes alot of sense now I think about the construction of a wall starter as they are designed to slide. Sounds like bonding in would be the best option and maybe a mechanical fixing as a belt and braces.

I've included a photo of the piers at present, they aren't toothed in but I'm assuming wall tied together as they don't seem to have moved over the years. The front of the garage is being rebuilt so the initial pier will be pukka.

 

[mattu27]

Just to update and hopefully get some more advice. The structural engineer has replied and said that the piers are to be built (bonded) into the original brickwork using 7N blocks (assuming toothing in every 3 courses?) So from the front it will be a full block and two half blocks bonded into the pier. If that makes sense.

Where the proposed timberwork is doubled up (i.e under proposed stud walling) it says to bolt using M10 bolts and form G washers. Can we use carriage bolts and G washers? Or is there another method? I think I've seen something called Joyner bolts?

Thanks

 

[Leofric]

Where the proposed timberwork is doubled up (i.e under proposed stud walling) it says to bolt using M10 bolts

what centres does your engineer have a telephone just ring them up and ask them these things.

 

[^woody^]

Where the proposed timberwork is doubled up (i.e under proposed stud walling) it says to bolt using M10 bolts and form G washers. Can we use carriage bolts and G washers? Or is there another method? I think I've seen something called Joyner bolts?

Thanks

Use any bolt, or threaded rod, or coach bolt, as long as you also add a wide thick 'penny' or square washer.

If these double joists are more than 150 deep, then put the bolts on the 1/3 depth axis (ie 1/3 down and 1/3 up) and stagger these, so one on the top axis and the next one on the lower axis etc. First one about 200 in from the ends, then 500 centres will be OK.