Time Bombs for Self-Builders: Small errors with large consequences

[Ferdinand]

This is an attempt to compile a list of small errors that are large problems to sort out later.

 

Though perhaps we need to be thinking about "deep" errors as well as small ones.

 

It has been inspired by my current need to replace both bathroom floors from what seem to be minor mistakes 10-12 years ago by the self-builder who added a top storey to thsi bungalow.

Ferdinand

Edited April 14, 2019 by Ferdinand

[Ferdinand]

Cause:

 

Probably either using a non-flexible tile adhesive in a room with ufh (bath 1 and 2), and/or using 8x4 sheets of chipboard for the subfloor rather than tongue-and-groove (bath 2).  Relatively minor mistakes 10-12 years ago by the self-builder who added a top storey to this bungalow.

 

Consequence 10 years later - significant contributer to need for 2 new bathrooms.

 

Bathroom 1 - movement and grout deterioration.

 

 

Bathroom 2:

 

Tiles cracking on an 8x4 grid, exasperated (maybe) by ufh only being over part of the floor increasing differential movement

 

 

Thought:

 

Skimp on the stuff you can see, not the stuff you can't see. And save on the deal, not the quality.

Edited April 14, 2019 by Ferdinand

[Jeremy Harris]

Good illustrations of a point that @Nickfromwales has emphasised a few times, that tiles laid on a boarded floor need a layer of glued and very well screwed marine ply fixed to the floor, to reduce the risk of movement.

 

I glued and screwed 9mm marine ply to both our upstairs bathroom floors, making sure that the ply joints were well staggered away from the underlying flooring joints.  This seems to make for a very solid floor, but I did use lots of PU adhesive and hundreds of screws, just to be sure as I could that it wouldn't flex, as our flooring up there is 600 x 400 travertine, which needs good support.

[ToughButterCup]

2 hours ago, Ferdinand said:

This is an attempt to compile a list of small errors that are large problems to sort out later.

[...]

 

How about;

• a row of piles 120mm 'out' - (allowed tolerance 130mm) meaning our front wall needing some creative thinking later this year [surveyor error]
• ICF blocks laid  - over a few meters - more than 20mm out of line causing significant expense and aggro extending the first floor joists
• walls built and left without concrete in them for 5 weeks, blowing down in a turbulent easterly gale in July ( cost several thousand )
• wall blocks hammered into line  (rather than being relaid) thus   causing fractures in the ICF and a huge blow-out - ( cost a few thousand )
• steels manufactured 300 ish out of line at one end, correct at the other, meaning several weeks delay and about £1500 of remedial work
• concrete slab laid to 25mm below FFL -  GOK how to sort that - posts to follow
• Getting out of bed in the morning feeling cheerful.  BIG mistake.

(PS, apologies Ferdinand ...)

[K78]

15 minutes ago, AnonymousBosch said:

 

How about;

• a row of piles 120mm 'out' - (allowed tolerance 130mm) meaning our front wall needing some creative thinking later this year [surveyor error]
• ICF blocks laid  - over a few meters - more than 20mm out of line causing significant expense and aggro extending the first floor joists
• walls built and left without concrete in them for 5 weeks, blowing down in a turbulent easterly gale in July ( cost several thousand )
• wall blocks hammered into line  (rather than being relaid) thus   causing fractures in the ICF and a huge blow-out - ( cost a few thousand )
• steels manufactured 300 ish out of line at one end, correct at the other, meaning several weeks delay and about £1500 of remedial work
• concrete slab laid to 25mm below FFL -  GOK how to sort that - posts to follow
• Getting out of bed in the morning feeling cheerful.  BIG mistake.

(PS, apologies Ferdinand ...)

 

Your posts really scare me sometimes. Any mistakes like that would blow my budget totally. 

 

I’m planning on using Durisol (or similar) and building myself with 2 joiners and 2 labourers. 

 

 

[ToughButterCup]

6 minutes ago, K78 said:

Your posts really scare me sometimes. Any mistakes like that would blow my budget totally. 

[...]

 

Mine is holed -badly- below the water-line.

So, a la @epsilonGreedy its DIYMax (but without his careful analytical approach), and TBH I go to work everyday needing to grit my teeth because I know SodAll about almost everything. But, slowly, too slowly, I'm getting more confident.

 

In the NW  @K78 ? I'll come and help with the Durisol if I can.

PM me if you like.

Ian

[joe90]

Not back buttering our kitchen and cloakroom tiles has led to a “hollow” sounding floor which will need to come up some time, but as the skirting and kitchen is now fitted it’s not a job I am looking forward to. Also not double boarding the downstairs ceilings has led to voices being heard between floors.

[TerryE]

TBH the only thing so far (after 16 months of occupancy) was that the TF construction crew put in cross bracing 50×75s (IIRC, but the might have been 50×100s) threaded through the ecoJoists during erection and these were nailed to the ecoJoists at the intersections.  On one cross-over in each of the main and guest bedrooms there is maybe a couple of mm flex which causes noticeable creak as you walk over them -- trivial to fix before boarding out, but we would need to lift carpets and do keyhole surgery to fix these now.  Even so, given that two floor creaks are my only annoyance, I think that I must have been lucky / all that anal attention to detail has paid off. 

[epsilonGreedy]

So far I can only offer a small error with significant consequences for my muscles. I wish I had paid the JCB man for an extra hour on foundation dig day to create separate mud piles to segregate my silt sub soil from the high quality top soil. Six months later I have to mine mud mountain on site to expose seams of top soil layered between sub soil and dried out turf.

[Sue B]

Our last slab was laid badly and dipped towards one corner.  Our builders sorted out the walls and the grounds contractors paid for the additional work and materials.  A year later we were ready to finish the real floor on the ground floor.  We laid the insulation and the UFH pipes.  The screed co arrived and told us that they couldn’t put the screed down because of the slope - the screed would be so think in one corner of the house the UFH wouldn’t work and also the cost would be much more. 

 

Fixing the problem entailed Peter crawling UNDER the UFH pipes and insulation, pushing additional insulation in appropriate places.  It was an absolute nightmare but we did it!

 

We just hadn’t twigged that the initial error, which had been spotted and corrected had additional consequences we had not thought about

 

 

[Temp]

Some assumptions that are unsafe and issues that can cost you a lot...

 

The grass verge out front is part of the highway.

The approved house will fit on the plot.

The plot is the size implied by the site plan/title plan/planning drawings.

There are services nearby so you must be able to connect to them easily.

There are no services across the plot.

It's a green field so no need to check for soil contamination.

The access road is a bit narrow (but my van fits down it so should be ok).

The seller says he will get planning permission for you.

It's ok to start building your house the day after getting planning permission (At least two issues).

Cutting down a nearby willow tree will stop you having to dig deep foundations.

If you aren't allowed to put surface water into the main sewer you can always use soakaways.

A self builder is always exempt from the CIL.

A self builder can reclaim any VAT they are charged.

Not using enough insulation.

 

I'm sure there are plenty more.

 

 

 

[newhome]

Things that didn't go to plan on my build:

• One of the builders 'fell off' (no one saw him) the scaffolding 10 minutes after arriving on site for the first time. He sued us as we had insurance whilst his employer (who apparently had no insurance) denied all knowledge of having employed the guy and said that we had employed him direct. The case was still ongoing literally years later. 
• buying cheap wall hung cisterns to save money - a false economy
• Buying a heating system that no one could install up here leading to lots of things being bought that weren't needed, and the system not working properly, then throwing good money after bad to try to get it fixed to no avail, until @Nickfromwales and @PeterW trawled all the way up here to fix it a few years later. 
• Putting the MVHR in the loft in an inaccessible place so I can't get up there to check it or change the filters
• Echo the issue with @Ferdinand's floor tiles. The main bathroom here has started to show that issue. They were installed by a tradesman so just not done correctly. 
• Not putting enough insulation in the floor. Walls and roof were well above building standards but the floor has the building standard minimum and with UFH it's not enough.

 

And not things I did but are costly beasts if they go wrong ... 

• not sending the VAT reclaim to HMRC within 3 months of completion leading to a refusal by HMRC
• not completing the CIL paperwork in the right order or not sending completion evidence in time leading to the exemption being cancelled

[ProDave]

The floor tile thing.

 

Due to complete ignorance, at the last house, I stuck floor tiles direct to ordinary P5 chipboard with UFH.  15 years later they are all still intact, no cracking, no loose tiles, no hollow sounding tiles, not even a crack in the grout lines.  Topps tiles must have saved the day by selling us a "flexible" tile adhesive that made them work when everyone says they should not.

[Ferdinand]

3 minutes ago, ProDave said:

The floor tile thing.

 

Due to complete ignorance, at the last house, I stuck floor tiles direct to ordinary P5 chipboard with UFH.  15 years later they are all still intact, no cracking, no loose tiles, no hollow sounding tiles, not even a crack in the grout lines.  Topps tiles must have saved the day by selling us a "flexible" tile adhesive that made them work when everyone says they should not.

 

I guess that the bathroom humidity might be an aggravating factor?

Edited April 14, 2019 by Ferdinand

[Temp]

Many years ago someone reported problems with their wet ufh system. The return temperature was very high causing short cycling. Turned out they had used an aerated screed.

[Temp]

Common problem is forgetting to tell the builder you want a tiled floor in the bathroom. If they find out early enough they can add more joists and set them lower to allow for thicker layers of WBP and the tiles without raising the floor level. 

[newhome]

32 minutes ago, ProDave said:

The floor tile thing.

 

Due to complete ignorance, at the last house, I stuck floor tiles direct to ordinary P5 chipboard with UFH.  15 years later they are all still intact, no cracking, no loose tiles, no hollow sounding tiles, not even a crack in the grout lines.  Topps tiles must have saved the day by selling us a "flexible" tile adhesive that made them work when everyone says they should not.

 

Mine is flexible adhesive and all 5 bathrooms upstairs are done the same but it's the 2 largest ones that are starting to show the issue (one more than the other). That may be to do with the size of the floor area or as @Ferdinand says the humidity as those are the 2 bathrooms I use. I don't use the others unless I have visitors. It's not too bad just now but I can see the grout cracking and feel them moving a bit where that is happening so I imagine it will only get worse TBH. 

 

[Ferdinand]

7 hours ago, newhome said:

all 5 bathrooms upstairs

 

This makes me smile every time I read it. It is what I do to fences, and @Onoff to gates.

 

You are very fortunate that you did not end up with a Borders’ version of the Palace at Knossos, complete with Minotaur in the basement.

 

You could recruit some toyboys and have a Scottish Seraglio.

 

F

Edited April 15, 2019 by Ferdinand

[Onoff]

Going with a floor to ceiling height in excess of 2400mm. Started off at approx 2470. As I replaced the ceiling joists anyway I should have set them lower. Thought I had it covered by buying in 2700mm boards to save myself a join in the plaster board. What I didn't account for was the line of slim rips needed by the ceiling. Took forever to do. If I'd had thought about it some more I could have had pretty much full tiles all the way up, lost the rips at the window sill etc.

 

 

Should have lowered the wall length shelf above the bath/basin to the height of the window sill. Wall mirror and shaver socket would have been better positioned for say someone shorter or in a wheelchair.

 

 

Should have brought the 2G window further in rather than leaving it level with the outside face of the cavity wall.

 

Should have bought one of these kits for doing the silicone years ago:

 

 

Should have mitred this trim joint:

 

 

Should have used grey solvent weld soil instead of the brown along the bottom of this wall. Could have saved all the worry and having to buy gap filling pvc cement:

 

 

Overall though the quality of my wall tiling is my biggest downfall. It'll make it a pita to clean on some bits and keep snaggjng the cloth I'm sure.

 

The shelf height thing above a close second though, the Feng Shui there is just wrong.

Edited April 15, 2019 by Onoff

[ProDave]

I am the opposite to @Onoff  We have a floor to ceiling height of about 2440mm.  I just love the fact i have been able to board all the walls without cutting a silly little bit off the end of each board.  The 40mm gap at the bottom will be covered by the skirting.

[Mr Punter]

58 minutes ago, ProDave said:

I am the opposite to @Onoff  We have a floor to ceiling height of about 2440mm.  I just love the fact i have been able to board all the walls without cutting a silly little bit off the end of each board.  The 40mm gap at the bottom will be covered by the skirting.

 

If you do the ceiling first the gap will be down to 25mm and the edges are better supported.

[ProDave]

3 hours ago, Mr Punter said:

 

If you do the ceiling first the gap will be down to 25mm and the edges are better supported.

I did. My 40mm gap at the bottom is with ceilings first.

[K78]

On 14/04/2019 at 16:28, AnonymousBosch said:

 

In the NW  @K78 ? I'll come and help with the Durisol if I can.

PM me if you like.

Ian

Thanks. I will take up on that kind offer. 

 

I like durisol a lot. It’s easy to work with. 

 

I’m going to take a look at isotex on the 26th before I make a final decision. 

[ToughButterCup]

OK, send me a PM as soon as ya like.

Ian