Attaching ply to pop top

[mbee123]

I'm struggling to attach a carpeted sheet of 3-4mm ply to the fibre glass on the interior of my pop top roof.

I put Sikaflex onto the fibreglass which I had keyed and pushed the panel onto it, it has stuck in most areas but has come loose at the far 'thin' end.

The fibre glass is not really dense enough for a screw to get hold, any tips? How have other people done it?

 

[phoenixfc7]

About to do the same. Was wondering whether hidden clips like Harrison trim supply would work? I was thinking of a combination sika and clips? Which sika did you use?

 

[mbee123]

About to do the same. Was wondering whether hidden clips like Harrison trim supply would work? I was thinking of a combination sika and clips? Which sika did you use?

The problem is the fibreglass is not very dense so i don't think a clip would hold.
I used Sika 221, to be honest it held in some of it, maybe I didn't get it spread evenly or keyed the fibreglass enough.
It may be better to do it in 2 or 3 panels which would make it easier to work with, I didn't want the extra join but in hindsight it is probably/easier.
I've also considered a strong sticky pad (3m etc) or adhesive velcro
Best of luck, let me know how you get on...

 

[phoenixfc7]

The problem is the fibreglass is not very dense so i don't think a clip would hold.
I used Sika 221, to be honest it held in some of it, maybe I didn't get it spread evenly or keyed the fibreglass enough.
It may be better to do it in 2 or 3 panels which would make it easier to work with, I didn't want the extra join but in hindsight it is probably/easier.
I've also considered a strong sticky pad (3m etc) or adhesive velcro
Best of luck, let me know how you get on...

I may try the clip on a off cut see if it holds, if not hte velcro idea is good combined with 221, the velcro holding it in place whilst the 221 bonds. I could staple the velcro to the fibre glass and ply, mine is a austops pop top and there is a good 2 inch of waffle fibre glass before the dense fibreglass top layer. I will let you know how it goes, got to dd 2 more lights first before I attempt it.

 

[airhoguk]

Personally i wouldn't staple the velcro as it may cause cracking in the surface. i'd go for some 3M Dual Lock velcro and then use the sikaflex

 

[mbee123]

I managed to sikaflex the thin end back on but it has come away in another area now so the sikaflex is not bonding well, so it is time to move to plan b.

I will probably try a 3M sticky pad or velcro along with Sikaflex and split the panels as I think they are too big and hard to work with but I'm keen to hear how other people have done this and what they have used so would appreciate a bit of feedback

 

[mbee123]

Eventually revisited this, I've completely removed the panel and can see that the sikaflex did not bond to the fibreglass very well at all, but did the ply

In the majority I used black sikaflex which didn't bond but the clear sikaflex bonded better but I'm going to have a rethink about the best way, and separate it into 2 or 3 panels, Interested to hear other people's experiences

 

[Salty Spuds]

Without seeing the job, could you bond some thin wooden battens to the GRP & then screw the ply to the battens? You could get some insulation between the battens as a bonus.

 

[DXX]

Without seeing the job, could you bond some thin wooden battens to the GRP & then screw the ply to the battens? You could get some insulation between the battens as a bonus.

As @Salty Spuds said plus I would seal the ply with a couple of coats of varnish. Moisture rises and any condensation is going to penetrate the ply otherwise.

 

[mbee123]

That's a good idea, but there is not much room between ceiling and bed board and the mattress is stored there, so the battens couldn't be very thick, maybe 5.5mm or 9mm

Below pic shows a small piece of ply at the front which has remained secure, and the fibreglass ceiling

 

[mbee123]

As @Salty Spuds said plus I would seal the ply with a couple of coats of varnish. Moisture rises and any condensation is going to penetrate the ply otherwise.

Thanks but having removed the ply I can see that the sikaflex bonded to it ok, but it didn't take to the fibreglass very well

 

[Salty Spuds]

Thanks but having removed the ply I can see that the sikaflex bonded to it ok, but it didn't take to the fibreglass very well

Which Sika are you using?

 

[mbee123]

221 originally, when it come loose i tried clear stixall which seemed to bond better

 

[Eclipse Custom Vans]

Thanks but having removed the ply I can see that the sikaflex bonded to it ok, but it didn't take to the fibreglass very well

You need to use the correct adhesive for the application. I've mentioned this many times here on the forum, sometimes the adhesive sticks to fibreglass ok, but sometimes not. It's better to err on side of caution to prevent problems. There are some primeless adhesives but we use primer and adhesive. We use trade adhesives in sausages by Industrial Sealants, Industrial Adhesives | Kommerling UK Sealants.

There are many adhesives which will work and many manufacturers, you just need one that is designed to work with Fibreglass. You may get away with one not designed for fibreglass but you can see what happens....

Also, I would fit strip battens first to the fibreglass then the ply to the battens.

Cheers

Ian

 

[Stuart Gane]

I have used sikaflex 291 marine adhesive sealant on a GRP (fibreglass) kit car with great success. The problem with GRP is that often a small amount of wax is added to the final coat of resin when moulding to prevent it staying tacky for a log period after the initial curing. I usually clean the surface of the GRP with acetone before bonding anything to it. Be careful not to allow the acetone to come into contact with the gel coat as it can sometimes dull the finish. If you want to fix wooden batterns to GRP use two part car body filler, it uses the same resin as GRP and bonds well.