Gap Filler Shrinkage

[Wassy]

We completed our owner built house three months ago, we used a professional painter.

A lot (most of) the gap filler on the architrave and skirting has shrunk to the point of almost non-existent. This has also happened to the gap filler the tiler used and the grout on the edge of the skirting board has shrunk.

There is no damage to the gyprock so I believe I can rule out any structural movement.

Can anybody please help me with: what has caused this, who's responsible for the repairs and what is going to be the best way to fix the problem?

[Master Splinter]

There's a lot of water used in house construction, either added on site (deliberately as in concrete or accidentally as in it poured with rain on the exposed framing timbers); you can expect the frame to shrink a bit over the first few years as all this water dries out, so having cracks open up isn't unusual.

Gyprock is sufficiently flexible so that it (mostly) doesn't show the effects of the frame drying.

But where you have an interface between materials with different expansion rates (gyprock/tile, gyprock/skirting) you'll always have the opportunity for the difference to become apparent.

Flexible sealants will only do so much - if you have filled a 1mm gap with No More Gaps, it gives you plus or minus 0.15mm (15%) tolerance for expansion/contraction - that's about the width of a human hair.

The gap sealers are promoted as wonder solutions, but in reality they fall short of perfection. It's not unusual for a standard timber frame to loose 2-3mm of thickness as the timber dries out - I think the expected shrinkage is in the range of 3-10% for construction timbers.

I think you'd find that an appropriately engineered expansion joint covering 3mm of movement would be more unsightly than a crack!

I'd give it another year or two - or three - for the frame to dry out and then go on a mad orgy of re-sealing if it bugs you that much.

[Honorary Bloke]

We completed our owner built house three months ago, we used a professional painter.

A lot (most of) the gap filler on the architrave and skirting has shrunk to the point of almost non-existent. This has also happened to the gap filler the tiler used and the grout on the edge of the skirting board has shrunk.

There is no damage to the gyprock so I believe I can rule out any structural movement.

Can anybody please help me with: what has caused this, who's responsible for the repairs and what is going to be the best way to fix the problem?

1. Grout doesn't shrink, but it may be flex caulk if it's at the edge.

2. You can never rule out structural movement. You will have it. You have already had it.

3. MS is right. Give it more time. If you repair it now you will be doing it again in a few months.

4. Also, beware the weather-provoked movement. I have small cracks that develop between the crown moulding and the ceiling in the kitchen every winter that repair themselves every summer.

[Wassy]

Thank you Master Splinter and Honorary Bloke, you have both given me plenty of food for thought.

I will do my best to ignore the problem and fix it in a couple of years (if I haven't forgotten about it by then).

Cheers
Wassy

[pawnhead]

No more gaps shrinks as it dries. The wider the gap being filled, the more noticeable it is, and it hollows when used over punched nails. Putty, or builders bog is better for nail holes.

[Wassy]

No more gaps shrinks as it dries. The wider the gap being filled, the more noticeable it is, and it hollows when used over punched nails. Putty, or builders bog is better for nail holes.

Pawnhead, what do you suggest for the gaps (sadly some are a little wider than I would have hoped for)?

[pawnhead]

If it's a gap that's flush. i.e. if the two surfaces are at the same level, then I'd use builders bog, or plastibond, or auto body filler, to get a dead flat non-shrink joint. Here's a picture of a window sill that I bogged up here just this afternoon:



I built the windows and frame out of some left over junk that I had, and you can see that the pink builders bog fills the gap, and all the areas where the two surfaces weren't quite flush. After hitting it with a belt sander, and hand sanding, you won't notice it at all when it's painted. The two timbers are glued and screwed together, so it shouldn't crack.

If you're filling an internal corner, such as where your skirtings and architraves meet the wall, then gappo is the only way to go. It's flexible and it won't crack as easily with different expansion/contraction movements between timber and plaster. And it's much easier to apply with a caulking gun.
If the gaps are big and it shrinks, then put some more on top. Instead of using your finger, which may leave a depression, use a scraper or a chisel to get it as flat as you can. A bit of soapy water on the scraper will stop the gappo sticking to it. If you get a bit of movement, then it may bulge out after a while, and between summer and winter, or humid and dry conditions, it may shrink then bulge, and eventually crack.

If you want a perfect job, then do it like they did in the old days before gappo/silicone/builders bog/max bond etc.
In other words, build it right in the first place, with no gaps and solid fixings for minimal movement.

[Carpenter]

Gaps, movement etc are an inescapable part of building, the trick is to learn how to deal with them & you can. The first thing is never use No.More Gaps or any acrylic gap filler. They are a crap product, cheap, nasty & ineffective. The trick is to use the new generation of polyurethene sealants like Sikaflex. They have a 25% movement capacity which is enough to accomadate most situations with ease. Sikaflex recommend you use the correct primer..a good idea if they say so. The downside of these products is they're not as easy to use as the acrylics & don't wash up in water, but the long term performance both inside & outside is the best you can get. When used externally to the manufacturers specifications these products will add years of life to the external building fabric because when used correctly they eliminate water entry, & thats where the trouble starts. Internally they move with the joinery etc so you won't get the cracks that happen with acrylics. If you want to have a go with the polyurethanes, its handy to use a plasterers small setting tool, some filling blades & even plastic silicone edge formers to get the correct finish. Wash up with turps.

[pawnhead]

The downside of these products is they're not as easy to use as the acrylics & don't wash up in water, but the long term performance both inside & outside is the best you can get.

They're also a lot dearer. You can get no more gaps, or the equivalent from Big W for about $1.50 a tube, and I believe sikaflex is at least five times the price. It's no doubt a better product, but most professional painters use gappo and you don't really get problems if the gaps aren't too big, and everything is nailed/fixed off properly.

[Carpenter]

They're also a lot dearer. You can get no more gaps, or the equivalent from Big W for about $1.50 a tube, and I believe sikaflex is at least five times the price. It's no doubt a better product, but most professional painters use gappo and you don't really get problems if the gaps aren't too big, and everything is nailed/fixed off properly.

A job I was on recently had a lot of detail that caused me to be at the house way longer than usual after the inside had been finished. After about 3 months of habitation, central heating going etc the gaps began to show, & after 6 months, everywhere acrylic filler had been used it had failed. Just because everyone else uses it does not mean it works, & I've banned it on my jobs. There may be situations where others have had no problems, but the performance limitations of the acrylic & the experience I describe above is enough for me to go with the poly's for their reliability. If your a professional you have to back up your work & I can't afford to gamble on low quality/cheap products that may very well cost a packet in reparation work.

[pawnhead]

That's fair enough. I'll stick to gappo though since I've never had any call backs over it. My building and joinery is good quality work but if I get slack, and need some heavy duty bog up solutions I may consider splurging out on the primo shyte.

[Carpenter]

John,
One area the poly is absolute gold is if you have big gaps to fill/seal. With the poly you can avoid a lot of cutting & scribing, one place I use it is where you get old door jambs that don't allow the architrave to sit flush with the plaster. Instead of cutting the back out of the arch so it can move in & sit against the jamb, (making an unsightly thin or tapered edge to the arch a causing it to not align with the skirting) I've found if you just let the arch sit against the plaster & diregard the jamb. You end up with all the irregularity/gap showing at the jamb but thats OK, just nail it & fill with poly/sikaflex, clean it up with the filling blade & its just trick. The poly is also a powerful adhesive so don't worry about the arch not holding the jamb. The poly is also capable of filling larger gaps & the trick here is to mask off the fill line to get a great edge. I'm probably sounding like a complete bodger, but I do close tight joinery work. Its just that sometimes, particularly in older restoration work or where I'm following up work by others, gaps are unavoidable & after using this poly now for a long time I believe it not only is a great solution, but it actually enhances the finish quality of the job.

[pawnhead]

Yeh, I see what you're saying, and I was just having a bit of a dig at you , but you didn't take the bait. It's undoubtedly a better product, and I once worked for a builder who wouldn't use anything else.
I've worked on a lot of old renos and I know the problems of jambs not being flush. If they're short, you can put a strip in, or rebate the arch, and plane a bit off the back of the skirt to match, or plane a vee in the back of the arch so you can tilt it (but then you have to compound the mitres), or leave a gap between the jamb and use some top quality Sikaflex to fill it. Similarly, if they're proud, and you can't afford to plane them down flush, you can plane an angle out of the back of the arch so it sits tight against the jamb, and tilts back against the wall (and again, compound the mitres to get them tight), or you can leave them square to the jamb, and leave a gap against the wall to be filled, but then you have to pack the skirt a bit where they meet, so that they're flush.
I generally try to get timber to timber joints tight, or I fill them myself if they're being painted, but it's the painters job to fill timber to plaster gaps. Of course a good painter will do it all if the carpenter is slack, and a slack painter won't fill anything at all unless you can fit your thumb in it. I've seen painters leave gaps all over the place, and get away with it, although not when I'm running the job they don't.

[UteMad]

All this talk about fillers your all sounding bodgy .....i have never used a filler for any joinery in my life........ LoL (i get the painters)

The more talk on fillers the bodgier you sound to the uninitiated.. Lets get into the big gaps that you can park the ute in that require backing rod that'll seperate the men from the boys..

cheers utemad

[Carpenter]

All this talk about fillers your all sounding bodgy .....i have never used a filler for any joinery in my life........ LoL (i get the painters)

The more talk on fillers the bodgier you sound to the uninitiated.. Lets get into the big gaps that you can park the ute in that require backing rod that'll seperate the men from the boys..

cheers utemad

Righty oh then! I once filled a gap so big.......! Cmon now Utemad, give it a go, you don't know what your missing. This stuff is a finish carpenters dream. You dont use it all the time, but for those tricky situations its the ducks guts. You just have to retrain your preconceptions that any filling is bad. When you can produce a finished job that will stand the test of time & still be performing in 5-10yrs time, well thats a job well done.