recoveringacademic

Steeling the Show. And an attack of wind

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Steels are up! After a fashion: with our build, there's always a twist so read on!

 

First have a look at this.......

20180131_084003.thumb.jpg.8c280717a391e8fb2015ecab351413c3.jpg

 

We finished late last night

20180130_174226.thumb.jpg.46be4d1261a0ecc382803e1013d3dbb8.jpg

 

SWMBO is really happy, and, to an extent so am I. 

 

The L shaped  steel structure is secured to the floor with Thunder bolts, and will be secured to the wall with 16mm threaded bar embedded in the Durisol block. So far so simple.

 

There was a gale last night , and attack of wind if you like : a useful gale, because it made me think hard.

 

The purpose of this post is to ask you to check my thinking and offer relevant comments before I talk to the SE and Durisol.

 

Many of you will remember the hiccup we had recently with the wall collapse (If not read this) And I am quite prepared to accept that that experience is colouring my thinking too much; but here goes.

 

For those of you who are unfamiliar with Durisol block, here is a brief introduction - to understand the rest of this, it's worth a quick look (Links to an image search for Durisol: you only need to understand what it looks like)

 

The vertical columns (steels) are attached to walls with threaded bar.  It's that 16mm threaded bar connection that concern me. Because

  • I cannot guarantee the continuity of the concrete within the Durisol blocks: it is that concrete into which I drill and attach the threaded bar and secure with Fischer Resin mortar
  • One of the holes I drilled through the blocks showed that there was no concrete there at all. (The drill went straight through and out the other side of the block)

 

Normally that lack of continuity will not not matter one little bit. But it does matter when the integrity of another structure depends in part on the attachment to the wall.

 

Proposed Strategy

 

  • Talk the issue with the architect (already done - strategy agreed)
  • Talk to you all 
  • Think it through again on the light  of the above and
  • Ring Tanners (our SE)
  • Ring Dursiol - maybe ask them to visit
  • Agree problem solution :
  • Talk to BC and ask for a visit before doing the following - 

 

Proposed  problem solution

 

  • Examine each of the current drilled holes with an inspection camera: checking to see 100% concrete continuity
  • Attach the steel columns to those holes which 'pass' the test
  • Create another series of attachment points by;
  • identifying 5 further attachment points and
  • exposing the concrete  behind the insulation by cutting out that insulation entirely
  • verifying the quality of the concrete
  • drilling into it to create five more attachment points (one per hole)
  • replacing some of the insulation and backfilling with cements and PVA mix.

 

Bit of a faff, but I have realised that technical reassurance that (in this case) the structure is self-supporting is not enough.

I need to know deep down in my gut that the structure is rock solid. The psychology is as important as the technical stuff.

 

 

 

 

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My only though, is if you bring to the attention of BC that there might be "voids" in the concrete fill of the blocks, then you re opening a huge can of worms, if Mr BC wants to be picky?  Find a solution without him?

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 If it has been confirmed technically (it looks self evident from pictures) that the steel is self supporting but you want to create a lot of grief and have possible unintended consequences, it's your perogative bit I would suggest you don't want to go there. If you don't have confidence  in your build, and can find evidence of isolated issues that might support that, then any responsible BCO should then take it to its logical conclusion. Do you want to go there? 

 

Your plan of attack is sensible in terms of actions, but as per ProDave, leave the BCO out. Leave Durisol out. Leave the SE out for now. 

 

That's not cutting any corners or introducing any new risk yet - the steel structure is self supporting 

 

Complete your course of actions and your analysis then determine if there are only a couple of isolated issues with voids, in which case you decide how to mitigate and move on (fairly simple).  

 

Are you saying the Durisol wall is partly supported by the steel or v.v? 

 

 

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Hmmm, @ProDave and @jamiehamy

 

It's Germanic-Me that's thinking of the BCO.... message understood

No, @jamiehamy, both structures are  said to be independent.  I know from experience that the house has stood many (named) storms so far with no ill effect - a few trades people have commented that any other build system (they know about) would have blown down by now. 

 

But the steels need to be rock solid too; and given this hiccup (thank God I found it!) I'm proceeding with caution.

Thanks very much for your help.

Ian

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Could you not put some small diagonals on the frame somewhere that won't be seen to stiffen it up.

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Is the steelwork to be insulated ? If so, just fire straight through the blocks and use a full vertical strip of mild on the internal face to stop the fixings crushing the durisol.

Its only the horizontal short sections of steel your fixing through yes? 

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Nick, all the steelwork is outside the heated envelope, and so there is no need to insulate it.

 

Nothing goes through the Durisol insulation, except the M16 threaded bar, but that terminates within the concrete. So there is a small cold-bridge, mitigated by the internal insulation.

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5 hours ago, recoveringacademic said:

One of the holes I drilled through the blocks showed that there was no concrete there at all. (The drill went straight through and out the other side of the block)

 

Have you looked with an endoscope to determine how large the void is? If you have been unlucky and struck a small cavity, is it possible to inject a resin into the cavity to fill it and also hold your metal stud?

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You may find, after speaking to your SE that you only need 5 bolts, rather than 5 (or what ever).  Depending on where the one without any concrete in the block is, it may not matter.

So first call is to the SE I would think.

 

Now remind me, why did you choose this construction method?

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18 minutes ago, SteamyTea said:

[...]

Now remind me, why did you choose this construction method?

 

Always up for a challenge old chap. Keeps me off the streets. 

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1 hour ago, PeterStarck said:

Have you looked with an endoscope to determine how large the void is?

 

Evidence, evidence, evidence. Exactly @PeterStarck. Camera on order, arriving tomorrow.  

Now that I think of it, there are lots of little jobs I have for such an implement.9_9

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It’s good that you know there is a void would be better if you knew why. There are only a few reasons logically why the concrete wouldn’t have flowed to the bottom

these being something is obstructing the void, a bit of durasol wood unevenly set concrete etc or the concrete couldn’t naturally flow down as there was a corner or something similar to flow round. Have a look above the void on the outside and inside of the wall for any obvious reasons why the concrete couldn’t flow. Is the void near the junctions between pours ? 

 

Dont inform any other agency until you are sure why there is a void like others have said you’ll open a massive can of worms.

 

That camera might be a mixed blessing. Don’t turn your walls into a Swiss cheese looking for other voids 

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1 hour ago, Bob said:

[...]

That camera might be a mixed blessing. Don’t turn your walls into a Swiss cheese looking for other voids 

 

My only focus is the support of things like windows, doors and steels attached to the outer skin of the house.  Normally the odd empty bit of Durisol block is irrelevant and never noticed because people don't look for it.  

The problems I face are not new or unique to Durisol: many others will have faced the problems and solved it before.  

 

It's just a matter of plugging away and having the courage  and humility to ask for advice.

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If you have identified a void why can you not fill it from above. 

Find bottom of void with camera, find top of void with camera mark area on face of blocks, cut a hole at the top, not a silly hole a mans hole 100 mm square, fill void with a strong wet screed mix

4-1 sharp sand cement vibrate the living daylights out of it. 

 

As others have said keep this on the qt. 

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On 31/01/2018 at 16:38, SteamyTea said:

Now remind me, why did you choose this construction method?

Most of us might have thought this, and isn't about time that someone invented the Tardis? You have to make decisions based on the best evidence at the time you make them. Others might make a different decision; you might do the same with 20/20 hindsight. We can't go back; only forward. 

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And the best outcome possible has been found .....

 

The camera shows a hole with solid sides all the way through. How can that be?

Easy

To facilitate cutting blocks exactly in half some blocks have a double central wall with a three or four mil gap between them. Normally blocks have a single web joining both sides. Those would be really hard to cut in half.

 

I had accidentally  put my drill exactly between the two central webs : and so drilled through fresh air.

Photo to follow.

I will double check by drilling 20mm either side of the original hole where there should be concrete (and back-fill with foam)

Yours faithfully,

Relieved of Lancaster

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1 hour ago, recoveringacademic said:

I had accidentally  put my drill exactly between the two central webs : and so drilled through fresh air.

 

Great news.

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For those of you who might be interested in Durisol, here's the detail from outside a block and from inside it.....

 

The blocks look like this : the gap between the two halves is where (the bit that looks like a crevasse) , unwittingly I drilled....

 

20180202_072906.thumb.jpg.fc6c27a94ec28d7177a3b6007ffa8cf4.jpg

 

and this is the image created by the inspection camera

 

BMPP0007.JPG.5110c09c27e8e35d5108442258cd57ca.JPG

 

As you can see, there is no void (other than that created by the drill) in the block. The inspection camera I used creates an image and a video which it saves to it's internal drive  (4 Gb): it hooks up to  a computer (in this case a Chromebook) and the tool acts just like any other external drive. Very easy to create an evidence base.

Now there's money spent on a tool which gave an instant return. 

 

 

 

 

 

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That’s really good news, but Sods

law if your drilling blind and you can hit a void cable pipe you will.

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Exactly.

That's why, taking advice from this Forum, I mark every place I embed conduit, and take a photo of it.  Some have advised I (we) take a good few photos because it's so easy at first fit (first fix) to 'get it wrong' . Getting it wrong' at this level would be really stupid.

 

Here's the relevant thread.

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On 02/02/2018 at 10:52, Bob said:

That’s really good news, but Sods law if your drilling blind and you can hit a void cable pipe you will.

 

Ian, I hope that you have a stud/cable/pipe scanner.  These should also pick up any pipe work near the surface.

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