Hot Weather and Wall Fastenings

For over two years I have had two shelf supports fastened to the workshop wall with screws and a well known brand of plastic plugs (brown in colour). The load on the shelf has barely changed over this period.

The other night while relaxing on the terrace we heard a very loud crash and on investigation found the shelf, contents and both brackets in a heap on the workshop floor. Fortunately no major damage ensued to any of the workshop assets.

On investigating further I noticed that the blocks used for the wall were warm to the touch. This is a consequence of the extraordinary long period of very hot weather we have experience in the UK. The plastic plugs had come out of the holes intact, still expanded and with the screws still in place.

So my thought is that the warmth in the wall has somehow changed the characteristics of the grip in the wall. This could be the plug plastic changing in some way i.e. going soft and therefore having less grip, or maybe the hole in the block work has expanded in diameter enough to lose the grip on the plugs.

It suggests my civil engineering was probably marginal in the first place and perhaps readers might like to check their installations to avoid a similar experience.

Thermalite, Celcon and similar blocks are poor material to gain good fixings in, best keep to the joints or better still span and fix to several joints with a batten and fix brackets to that.

Emgee

I always use Gorilla glue (or its much cheaper versions). Squirt some in the hole and then some in the plug and assemble as normal. I have never had one shift after that treatment.

I have had similar problems to Alan in the past. Once fixed with the expanding glue, I have had no further problems.

Andrew.

Storage heaters had to be fixed with fibre wall plugs, plastic ones have caused injury’s as they were known to have given way allowing the heaters to tip off the walls.

Anybody here remember "Philplug" (no connection) an asbestos based fibrous material that you used to mix with water and roll in your fingers to form a squidgy plug that was then pushed into the drilled hole? On more than one occasion I can remember pushing too much of the mix into the hole and ending up with the screw shearing off, but if you got it right the screw never pulled out. Back on topic, I have found from time to time when removing fixings in plastic plugs that they sometimes pull straight out without even having to turn the screw but I have always attributed this to the incorrect plug to hole size having been used.

Phil

Edited By Philip Rowe on 25/07/2018 16:35:22

Oh yes.

You were supposed to spike it before it set :O)

I think this prolonged heat is doing a lot of damage. Two out of six "Velux" roof windows in my house have cracked glass. The house is old (1860) but the windows where fitted forty years ago and have never given any trouble.

Alan's wall getting distinctly warm on the inside suggests it might not be that well insulated. If that's the case, it will tend to warm during the day and cool overnight. The cycle repeated many times over a few years will tend to loosen the grip, with the weight of the shelf working to ease the plug out of the hole a fraction of a millimetre each cycle. Eventually the shelf may lever the plugs out completely.

Don't ask me how to fix it - putting up shelves is above my pay-grade. My worst experience was a couple of square feet of plaster falling off a wall as I tightened a screw. I haven't been asked to help with DIY again.

Aka Rawlpastic. I still have some. Mine has a spike to make a hole down the middle for the screw, Very little is needed.

Philplug great stuff, when I worked for pilkingtons we used nothing else for fixing mirrors & splashbacks it didn't matter if the hole was slightly off as long as you had the collar on the mirror, you got a pointed bent spike with each pack to start the screw off, [I never ever broke a mirror & fitted 100s in my time] & yes I once fitted them to a bedroom ceiling!!

I have had a fixing failure due to the heat. It happened on a southwest facing wall which has a strong galvanised bracket supporting some high level fencing and a Montana Rubens Clematis supported by a steel cable, the wife went out this evening to water the garden and found the steel bracket hanging off the wall, the “rawlplug” fixings had parted company with the brickwork. The fixings were 12 mm type rawlplugs and the brickwork had been subjected to full sun every day and was consequently very warm, I presume the plastic of the fixings became soft and pliable with the excessive heat, 30 degrees today so no wonder. Rectification has already taken place, I cleaned the holes out, slackened the rawlplugs on the bolts and then injected resin fixing compound into the holes and reattached the bracket and fixings and tightened the bolts, the resin should hold the bracket now, the instructions on the resin stated that at the temperature today the working time of the resin was about 4 mins and fully cured within an hour. Fortunate that I had half a tube of resin left over from a job only three days ago. I realise that they don’t advise the use of the resin with plastic fittings but as a first aid measure it will be interesting to see how long this repair lasts.

Dave W

I have Spur Shelving screwed to the brick wall with plugs and screws, supporting 1978 VX490 back axles, gear boxes and huge amounts of other storage, they've been there with similar loads for over 30 years, if you want to support this kind of load long term you will need to oil or grease the screws, if they install without then heavy stuff may drop off without lots more screws than really necessary.

For welding sets and other concentrated loads I often added Rawl Bolts as the top fixings, I've never had anything fall off.

I think you went for screws and plugs which were too short/small for the job, state your screw size and length and plug sizes.

Edited By Nick Hulme on 25/07/2018 21:06:06

I think some of the problem with my bracket arrangement was that the load was not only in the vertical plane, that is shear, but also a major element was pulling the bracket laterally away from the wall and the bricks getting so hot degraded the grip characteristics of the fixings which 12 mm diameter with M8 bolts compressing the plastic sleeves, the fixings themselves are 80 mm deep. Hoping now with resin all should stay secure, checked security after the resin cured and now solid as a rock. Your bracket arrangements would appear to be all in shear which is the ideal loading arrangement.

Dave W

Hi Alan,

Right now, down here in the antipodes, it has been a bit chilly. However, we do get warm weather.

In a thread about my use of fishing line for clocks, (04/07/2014) of this (lengthy) …

**LINK**

fellow Victorian and Forum contributor John McNamara drew my attention to the Gremlin called Creep.

It left lots of egg on my mush. Marinated in design applications for years, a knowledge of empirical time/temperature/stress curves was essential. I had simply taken for granted that fishing line was a sufficiently tough monofilament (molecular orientated) to resist creep.

I was wrong.

Therefore, it seems clear that your shelf fastenings have suffered a similar outcome.

Stay cool

Sam

What is the load rating given by the wallplug manufacturer? I've never assumed those things (any manufacturer) are suitable for a shelf carrying (or likely to in the future) any kind of load. Always gone for expandable anchors for that kind of use (metal toggle/swing/collapsible etc).

That's if I can't find some suitable wall-studs in the right places to screw directly into of course.

deleted

Edited By Sam Longley 1 on 26/07/2018 08:09:39

Plastic plugs never were any good. I always tap a bit of wood into the hole, always worked.

Points taken about the suitability and quality of plastic type fastenings for heavy loading.

Dave W

Is this really true guys? Promoting the use of "PhilPluG" material? Asbestos based? I too used to fob off the dangers of asbestos and not to worry about it.

I sat at the bedside in a hospice of my only brother in January of this year whilst he died of mesothelioma, one of the three main asbestos related diseases. He had NEVER worked with asbestos in his long working life yet had become infected somehow.

This experience would change anyone who claims to be a human being I can assure you and would never ever promote asbestos in the environment again.

Sorry if this offends.

regards

Ian.

Ian, I know how you must feel, I was exposed to asbestos in the 60’s and 70’s, no protection, the Crown is good at telling everybody how to look after their workers, not so when it comes to their own. Always at the back of my mind especially as my brother in law has plaques of asbestos on his lungs from industrial exposure, again no protection, same employer. I am with you on the using of any asbestos related product is definitely a no no.

Dave W