Fibreglass Application Frequently Asked Questions

There are many misnomers to be found all over the internet surrounding fibreglass, from how to apply it and how easy it is to apply, to the length of time required before adding fish to a newly fibreglassed pond, this FAQ answers them definitively.

1. How much do you charge per square metre for fibreglassing?

Due to the enormous variety and technical complexities of our GRP and polyurethane foam installations, coupled with staffing requirements and UK locations, we do not price any of our work on a per square metre basis.  All of our work is priced exactly to the specific requirements of every unique application. This guarantees you the best price for the right job!

2. Can fibreglass only be applied during warm weather?

No, fibreglass can be applied in virtually any temperature extremes subject to the correct addition of the hardener. During colder temperatures an accelerator can be added to the resin prior to the hardener to speed up the hardening process. GRP Lining Services offers a year round service.

3. Is it true that fibreglass can not be applied over damp or wet surfaces, or if I have a water ingress problem during the construction of my pond?

No. High quality polyester resins coupled with the correct thickness of matting applied over the damp will still harden regardless of being applied over a damp surface. No long term issues regarding longevity are known when the fibreglass is laid correctly. Pools with serious water ingress can still be sealed and left 100% waterproof by placing a barrier between the water and the fibreglass. (i.e. PU foam). This does need specialist attention however. Please discuss this method of application with us.

4. Is it it true that I have to fill my pond two or three times BEFORE I add the water that will contain the fish?

No. Modern, low styrene emission resin systems, correctly laid, will not need endless filling and flushing. A simple rinse down a day or so after the fibreglass is applied is sufficient. GRP Lining Services has never known a case of styrene poisoning in fourteen years of trading using our GRP systems.

5. What surfaces can fibreglass be applied to?

Concrete, render, polyurethane foam, brick, mortar, rocks, wood, metal (window frames etc), plastic (pipe work, bottom drains, skimmers) are all appropriate for the application of fibreglass. No fibreglass systems should be applied to bitumen painted surfaces without prior treatment. Polystyrene MUST not have fibreglass applied to it. Butyl and pvc liners can have fibreglass installed over them in certain circumstances.

6. I want to extend my pond, can the new fibreglass be adjoined to the existing pond?

Yes it can. Specialist treatment to the existing fibreglass is required to ensure a good bond but it is perfectly feasible to do this.

7. Polyurethane foam seems the modern way to pre-line the pond instead of rendering but will it crush under the weight of the water?

Our PU foam / GRP systems will not crush or lose insulation values at any depth of water, size or shape of pond.

8. Does the cement render need to be sealed with G4 prior to fibreglassing?

No. Cement used in the render mix will not react adversely with polyester resin. Save your money!

9. Can fibreglass be applied directly over blockwork?

Yes, but..... blocks should be sealed with a primary layer of resin before the main 'lay up.' The pointing should be flush jointed and any broken corners on the blocks should be filled with a sand/cement mix. The patterning of the blocks will be visible behind the fibreglass but is undetectable once a coating of algae is established over the fibreglass. By the time this primary layer of resin is applied and hardened, coupled with the time spent on pointing the blockwork perfectly it is more cost effective to use polyurethane boards instead.

10. Can the fibreglass be installed in any colour?

Yes, however. Darker colours are favoured by fish keepers in the name of helping the fish feel more secure against a dark background colour such as black.

11. Is fibreglass easy to install yourself?

If you have a very formal shape to apply the fibreglass to, have a very practical frame of mind, optimum conditions to work in and patience then it CAN be done. However, if something begins to go wrong you need experience to deal with problems. Ask yourself if it's worth the risk in what you might save when attempting a DIY job against using professional expertise. See our 'Case studies page' to see what CAN happen when DIY attempts go badly wrong. Compare the professional finish to a DIY attempt.

12. Do I fit my coping stones before or after the fibreglass?

Preferably afterwards. If you install the copings prior to the fibreglass make sure the mortar bed is flush pointed underneath.

13. How soon after the fibreglass is installed can I fill the pool and add fish?

During warm weather we suggest a couple of days cure time. During colder weather this time may be up to a week. You will be advised about this dependant upon the ambient temperatures expected once the installation is complete.

14. I've left my pool empty for a few weeks before adding water, when I tap the fibreglass on the walls and floor it sounds hollow behind it. Is this a problem? What has caused this?

Polyester resin used in the laminating process is not strictly an adhesive that 'sticks' to the surface it is applied to. There is a natural percentage of shrinkage as the fibreglass hardens and this can cause the GRP to release from the surface it was applied to. When the pool is filled with water the GRP is held to the walls and floor by pressure. When the pool is filled, the fibreglass is pressed back into place. Ponds with a water ingress issue can lift our systems by up to 12 " without breaking. This is called 'flexural strength'. The fibreglass will return to the position it came from without a problem.

15. How strong is the fibreglass on my pond?

Generally only a serious physical attack using sharp objects will damage the fibreglass. It's even been tested as being able to withstand the onslaught of young children in a strop!!. However, do not drop anything heavy or sharp onto the surface especially during the curing process.

16. How do I clean the fibreglass during maintenance?

The fibreglass will only need to be cleaned to remove stubborn algae accumulations. This can be done with a pressure washer if required. Otherwise, a stiff brush and a hosepipe will remove loose algae. Your fibreglass should need no other treatments for many years to come.

We are happy to answer any further questions regarding fibreglassing systems and application processes with you, should you wish to get in contact please visit our 'contact us' page for options.

This information is based on fibreglass systems installed by GRP Lining Services only.