Quick question on packing sole plate

[janedevon]

Hi there

 

really quick question as to best product to use to pack out soleplate.

 

sole plate being laid today by timberframe company, and where it's not exactly level it's been packed out with wedges, they say our guy needs to come and fill the gap, any suggestions? Something in a tube/ gun I guess, going to be hard to get cement under there?

 

many thanks

 

[Jeremy Harris]

This needs to be a really good sealant to make that joint 100% air tight - frankly I don't like the idea of there needing to be packing under there anyway, as it's asking for poor airtightness and indicative of a foundation that wasn't properly laid.  It also means that the frame is putting point loads into the foundation, rather than having the load evenly distributed.

You need to seal this gap up to absolutely, 100% stop cold air getting in under the sole plate from outside, anywhere, as that risks cooling it and causing interstitial condensation from vapour movement that could, in time, cause the untreated timber to rot.

Can you get at both faces of the sole plate?  If so, then injecting low expansion foam as deeply as you can get it, from both sides, may be an option.  It's going to be fiddly to do, but you are where you are so have to deal with this somehow.  After injecting low expansion foam and after it's cured, then sealing the remaining edges with a decent quality PU or MSP sealant will stop moisture penetrating the foam (the foam is fairly air tight, but will most probably be vapour permeable).

[janedevon]

Thanks, yes it's a bit annoying however the frame company say that it is common in their job to do this they said most jobs they go on are the same, annoying to say the least though, so I'm left with this gap to fill between my dpc and the sole plate, should I try to get it filled under the dpc layer ? Or on top going to be tough which ever way it's not huge gap but theres a lot of it to fill!!!

[Jeremy Harris]

I'd have to say it's not at all common, it's very bad practice.  Our build is a timber frame and was fitted to a proper foundation that was laid absolutely flat.  Anyone laying a foundation for a timber frame building knows that the foundation has to be dead flat and level, it's been common knowledge for decades.

There really is no excuse for poor workmanship that can have such serious consequences on the life of the building and for the thermal integrity.  Having any gap under the sole plate is wholly unacceptable, especially as filling and sealing such a gap post-erection is both very difficult and unlikely to be 100% effective.

Best to try and get the sealant to totally, 100% (absolutely no voids), fill the space between the sole plate and the DPC.  It'll be a pig of a job to do well, and will probably need some thin nozzles fitted to a decent foam gun to ensure there's half a chance of getting LE foam right into the slimmest gaps.  Any gap at all, no matter how small, will act as a condensation locus when external water vapour moves in through it, and the impact is that the sole plate is likely to remain damp in any such area, with the inevitable risk of rot.

[ProDave]

We had a "similar" issue. but it wasn't because the foundation walls were not flat, it was the timber for the sole plate came from the merchant warped.  The builders bolted it down as hard as they could and still it was clear of the wall in places. It wasn't until it had more weight from the frame on it that it finally "bent" itself flat.  Timber, don't you just love it as a building material?

[janedevon]

That is another point one of my builders stated, a 12m run of timber may be a bit warped or not exactly straight going to go with a bit of foam before walls go up.

[Alex C]

Packing under a sole plate might be far from ideal but it is pretty common practice. Very few frames are put up on power floated slabs, you are normally reliant on a block layer to put down an accurate coursing block course. It is always going to be easier to fill a gap as a sole plate is fitted rather than trying to fill it afterwards.

[ProDave]

When I was down south and we had an extension built (of masonry) it was normal pratice there to bed a wallplate on mortar, so it was fully supported.

Up here sole plates and wall plates are fitted "dry" to the top of the wall / Foundation. I wonder why?

[Alex C]

The mortar will not take the same point load as a concrete block and would need to wait for it to fully cure before putting the rest of the frame up. It is fairly normal to specify a 7kn concrete coursing block that the sole plate is then fixed in to. Timber frames often have point loads from steel posts or cripple studs that would be spread more evenly in blockwork.

[Declan52]

Always bed the wall plate on mortar in NI as well. Easy way of ensuring there are no gaps and it's perfectly level.

[janedevon]

Yup mine is on a course of 6 inch blockwork allowing ffl inside at least the blockwork was square  just a few gaps to fill and bearing in mind it's above dpc hoping won't be a problem

[Jeremy Harris]

As above, it is essential that any gap, however tiny, is filled.  The last thing you want is water vapour freely moving in and out under the sole plate and condensing into water when  the conditions are right.  This is pretty much what caused so many early timber frame failures in England back in the 70's when a mass builder started building timber frame houses without understanding the interstitial condensation risk.  Some didn't even make it to the end of their 10 year warranty before the frames started rotting out.

[hrc]

If the combination of a level concrete foundation and a straight timber soleplate is difficult to achieve a perfect fit would it not be possible to lay a neoprene or EPDM strip, say 3mm thick to take out any imperfections?

[Jeremy Harris]

15 minutes ago, hrc said:

If the combination of a level concrete foundation and a straight timber soleplate is difficult to achieve a perfect fit would it not be possible to lay a neoprene or EPDM strip, say 3mm thick to take out any imperfections?

Yes, you could do, or just do a decent job by either getting the foundation flat in the first place or by laying a bed of sealant on top of the DPM before placing the sole plate down. It's primarily a poor workmanship problem, one that's annoying because it's awkward and difficult to fix afterwards.

It's not difficult to get a dead level foundation, it just has to be floated off level.  This is done all the time: our entire slab was floated off dead level, so it's not exactly hard to do.

[hrc]

Jeremy, I know you've said this before but in practice how level and how straight/flat :+/-0? 1? 2? Over what sort of distance (if I get my planning) I'll have 12.1m

I've worked on site (sparky) so if it can easily be done I need to get my builder trained. I take it from your comments that MBC DO get them level/straigh?t

[Jeremy Harris]

Ours was flatter over the longest length that could be measured (about 10 to 12m or so) than the accuracy that a laser level could detect, so better than around  +/- 1mm (laser level accuracy is usually +/-3mm over 30m).  We (or rather our floor tiler) spent around 40 minutes trying the find the high spot to work his levels from then gave up, concluding that there was no high spot that he could find.

In practice the combination of timber deflection and the DPM deflection may well take up 1mm, and anyway I doubt if anyone really levels a frame to better than a mm along any one side, so if it's been wedged up to make it level it's fair to assume that the error is several mm, and it frankly isn't hard to get a foundation level to better than that.

[marmic]

@janedevon  may I ask please what was your conclusion was?  - if you are still on here?

 

if anyone happens to be reading this over their coffee and has found the easiest/best product and method to do this would appreciate some knowledge from experience please 🤞.

 

Just been scouring 'screwstation and toolfix' websites and will continue looking once I've sent this -  currently very undecided what to use as quite a selection it seems. Thought I'd put the question out there again but bit of a long shot as need to decide quick and pick something up shortly this morning!   Can't be too runny of course as it won't fill the gap and will just pour out.  Only possible to get to it from inside - but don't want it coming out the other side either - there is a gap there (larsen truss wall panels) which will be filled with extruded installation before cladding.  The 'soleplate gap' is outside of the internal air tight layer.  Need to get stuck in and completed before Monday (amongst other things) when dpm/floor insulation work etc commences. 

 

• Non shrink grout is the official line from the timber frame manufacturers - with my skillsets probably needs to be in a cartridge or foil sausage to pump into small gaps (between DPC and sole plate)
• Their site install team (very experienced) have suggested however most people foam it (but stopped short of recommending).  Right or wrong? Thermally better, easy, and will hold / fill gap no doubt and probably go further in. Low expansion foam I like the sound of for doing the job, but it's limited structurally of course.  Any thoughts please?
• Packers are spaced as designed and level is within timber frame manufacturers stated [sta] tolerance - and they were happy when preconstruction check took place. Still small gaps of course
• Install team actually commented our base is probably in the top 5 for level tolerance of any project they've installed - from self build to large developers. But still doesn't make it perfect with gaps present, however small, anywhere lower than the highest points.
• From comments I've heard/read in various places it seems quite likely the truth is many soleplates probably end up being fixed out of level pinned down tight to whatever is there - not right either!

   

No comments please about what should have been - yes we know!  This isn't helpful!  Couldn't have a raft/slab/power floated foundation etc due to soil conditions - would have been so much simpler!

Unfortunately perfect groundworkers/brickies are like rocking horse #### it seems -  and many think they know better.  The company we used did lot's of things well but where they didn't (number of items) they didn't like being told! Levels for example they brazenly stated and argued were within tolerance on scope (fortunately I had the sense to state less than actual max), which they weren't, and clearly didn't like the fact I was capable of checking!  Short of a blazing row (was very close) or worse, and/or a long winded expensive court case /  delays to whole project etc there was nowhere to go really.  If this was traditional masonry build it really would have been fine. In addtion to clearly not fully digesting written scope / drawings and detailed conversations also made extra work for himself (not me) by ignoring suggested sequence due to unusual site conditions (he knew better, or thought he did!).  We came to a commercial agreement on items I agreed to put right (not enough in hindsight) and remedial works completed despite not enough hours in a day already!  Looking at it optimistically however maybe the cost was lower than if we'd been able to find somebody who could have completed work to perfect exacting standards - but would we have been able to afford this, and could it have been done in time?  - probably not based on other responses. Bottom line is we are progressing and all will be fine.....................not a complicated project thank fully...  Maybe I'm over particular, but I know what i want/expect!  The groundworks stage has put me off ever doing this again unless money was no object!  I work in the construction industry anyway (for a manufacturer - not on the tools and not currently housing) so know the score and how things work - which is probably why some so called trades have been a bit reluctant to work on our project as they know I know!  not a bad thing as probably helps sift out the dross!  Have had 3 people actually now say 'you know too much'!  So I can only assume there's a huge amount of poor workmanship still hidden out there in housing, big and small........   rant over!  

[Nickfromwales]

How many places need packing, and by how much? 
 

Some pics of the main offenders would help, and also what’s the other side exactly, where you can’t get to, to gauge the impact of an expanding product going that way. 

[Marvin]

How much are the gaps 5mm? 30mm? 

 

Not sure if you are saying if you can get temporary access to both sides when filling?

 

In my humble opinion non-compressible material should be used under every vertical stud position as a minimum.

 

I always used a dry sand and cement mix 3:1 just damp enough to hold together when squeezed in my hand to pack gaps like that. Packed in tightly in gaps and allowed to set.

 

Good luck M.

[marmic]

thanks both for your thoughts.  6-7mm ish - zero between sole plate and dpc. Zero of course being the high point of coursing blocks.  Just over 40m of soleplate - but gaps not all round thankfully. External horizontal insulation not in yet (arrowed green). This will be cut and sealed in with the required 10mm gap to larsen truss panels and closed off with compriband/similar.    Cladding last.

 

blue is dpc/dpm

red air tight membrane lapped and sealed to walls and for screed

 

 

 

[marmic]

ah...   not thinking - I'll  'post'  my horizontal insulation in first today - it's here ready and waiting.  Each with a decent bead of GP sealant.  This solves the problem of overflow!

 

But still need to decide what to put in the gaps tomorrow  🤔

[newbuild upnorth]

ive just been using sika 111 GP non shrinking grout to fill the gap around packers for steel columns, this would be the solution if you could mix it slightly dryer and pump it in with a mortar gun, might make a bit of a mess outside until you get the mix right but it is definitely made for the job.

 

will it be over the dpc? grout wont be any good if its not as I reckon it might bridge damp over time but is definitely the right choice if its isolated with dpc between the blocks and the timber

[Nickfromwales]

Not seen a section drawing like that before. The entire external leaf and all your façade cladding etc hanging over a 10mm gap with some comp'band seems odd to me; most are sat on the insulation, and that is flush to the masonry or Marmox.

 

If you can get to all that area currently, then I would set that insulation block in, against a fat bead of 330FM foam to act as a shutter and better seal the gaps under the twin wall. Then to fill the gaps I would drill down into the soleplate, using a handsaw blade inserted above the DPC to ensure that it doesn't get punctured by the drill bit, say at 10mm dia.

 

I'd then introduce about a teaspoon of 50/50 water/pva primer and then the same qty of D4 PU flooring glue into the same hole (500ml bottle have a nozzle that you can push into the hole and the glue is reasonably 'runny') but less is more with this so do some trial and error before you squirt too much in and it goes crazy. 

 

If the undulations are over say 1000mm, then I'd drill every 200mm, dead centre of the sole plate, and repeat as necessary. Youll need to hoover out the sawdust or use a blower, so the hole is clear for the glue to drop down.

 

The D4 glue will love the bit of moisture from the priming and cure/expand like nobody's business, and it'll go off very hard to give you the result you want. Normal builders foam will be quite soft, and a waste of time here if you want strength as well as gap-filling.

[marmic]

thanks all - walls already on..........not a common detail (bit belt and braces if anything - certainly won't have any damp!) but BC approved, structural warranty approved, and calcs bring us to passivhaus high performance.  Larsen truss panels (which are mainly insulation!) have all the load on the 140mm.  The 'outer' brickwork is just to look nice and hold the insulation & persicope vents!

 

would have been nicer off a raft but had to be suspended.  Original plan was preinsulated concrete planks which would have been a lot easier - but had to change after manufacturer moved the goalposts - dpm capability / level tolerance / required topping.

[saveasteading]

There shouldn't be gaps... should be level. But at least they have packed them as some might just have built squint.

 

We have sole plates going onto an existing slab, with 20mm variation.

So we will pack with plastic packers: probably horseshoe shape. Then inject non-shrink grout possibly from both sides, and then "point" the outside, pressing it in.

BUT for the big gaps I favour dry pack. A sharp sand and cement grout, with just enough water to make it workable.

This way it can be forced under and packed tight so it is known to be  100% full and dense, and the low water means it won't shrink.

That might work with dry-mixed expanding grout, but it won't help.

Diy, as only you really care.