Leaky roof

[Richard Warren]

Hi there,

 

I have a 1973 Harborough Marine narrowboat which has a GRP top. In the rains over the last week (especcially last night) I have found two leaks in the roof which are causing me some concern. There is also a leak where the GRP sides meet the Gunwhale. I have tried filling them with Marine Sealant but the paintwork is not much cop these days and the water still seems to get in. Does anyone know of something like a paint on sealant which would do a decent job for a couple of months until I can do a re-paint in the spring? The leak in the gunwhale I think is actually coming through the steel (strange I know) but I have sealed everything around there. Any knowledge of a good product would be great.

 

Richard

[Guest]

Hi there,

 

I have a 1973 Harborough Marine narrowboat which has a GRP top. In the rains over the last week (especcially last night) I have found two leaks in the roof which are causing me some concern. There is also a leak where the GRP sides meet the Gunwhale. I have tried filling them with Marine Sealant but the paintwork is not much cop these days and the water still seems to get in. Does anyone know of something like a paint on sealant which would do a decent job for a couple of months until I can do a re-paint in the spring? The leak in the gunwhale I think is actually coming through the steel (strange I know) but I have sealed everything around there. Any knowledge of a good product would be great.

 

Richard

I have used "panel seal" to good effect on steelwork, and I assume it would work equally well on glassfibre. It is available in mastic type tubes, and I am certain I have seen it in Halford's. Other decent motor factors should sell it.

[bottle]

Hi Richard

 

Where the water is coming in at the gunnel (gunwale) level may not be where the leak is on the outside, there could be capillary action the actual leak on the outside could be some distance away.

[Liam]

On the Harborough boats, the glassfibre cabin is fixed to the steel which has a lip attached.

 

Check to see that the screws/bolts are correctly fixed and not rusting, and also that the lip isn't rusted either.

 

Although it's quite hard to get into the little space to do this it's well worth doing.

[Keeping Up]

I could go on for ever about the places our old 1969 Harborough boat Thistle used to leak. Of course, because the GRP was a double-skinned sandwich with foam between two solid skins, the water would emerge many feet away from the leak. Here are just a few examples, starting from the top:

 

1. The handrails. Later roofs had a series of solid upstands for the handrails (which were then just straight wooden poles). If the rails were attached properly they usually didn't leak. If someone had drilled too far into the upstands, they leaked. Earlier roofs (like ours) had no such upstands, instead the handrails were shaped, and they were attached by means of screws through the roof from below. The previous owners used to sleep with their sleeping bags inside bin-bags. Every screw leaked all the time; just about the only cure is too apply copious amounts of very good mastic (eg Sikaflex) at regular intervals.

 

2. The joins in the roof. The roofs were in several sections, often butted together with a strip of steel screwed over the top of the joiin. The sealant would leak, and so would the screws.

 

3. The roof itself. There may be cracks or old screw holes anywhere.

 

4. Things attached to or through the roof. In our case these included a TV aerial, the chimney, s couple of brackets for things, and of course the rear hatch.

 

5. The join between the roof and the sides. Although the roof overlaps, there can be a gap through which water will enter by means of (a) wind ( general wetness © osmosis and (d) magic. Sikaflex was useful for this one.

 

6. Joins in the sides (as for joins in the roof)

 

7. The side itself. There may be cracks or old screw holes anywhere. Thistle had once had a name-board attached; one of the 4 screw holes leaked, the water dripped on to my feet, 10 feet away, when it rained. It took a long time finding the 3mm hole (black hole, black paintwork, etc)

 

8. Things attached to or through the sides. This includes the windows, which deserve a page to themselves (leaky screw holes, frames that expand in the heat so that their sealing leaks, leaks through the actual frames, leaky rubbers, etc etc)

 

9. There were lots of screws holding the sides to the gunwales. They all leaked.

 

10. The metal of the gunwales was slightly rusty, there was no hope of ever sealing the top to the sides properly without removing it and cleaning everything up. Impossible. Water came in by the usual combination of win, osmosis, magic, etc etc etc; every time it rained we knew just where to place half-a-dozen saucepans on the lounge floor to catch the drips. Instead I sealed a thin strip of wood to each of the sides, along the whole length of the outside of the boat; it covered the leaky attachment screws, and was then sealed to the gunwales all along as well. It worked pretty well.

 

Well there's my top 10. If that's not enough just let me know, I can probably remember another couple of dozen if I think for a few minutes.

 

Allan

[tyse]

hi richard , try Flexacryl , can be applied in wet or dry conditions ( i've used it to seal roofs in pouring rain)

read pdf in link for more info , will stick to a wet blanket

 

http://www.screwfix.com/app/sfd/cat/pro.js...4&id=10990#

[phishphace]

hi richard

 

we are in the same boat as you [well not quite literally ].

 

in august we purchased a Harborough that had water leaking in through the roof, windows sides etc, and we are currently trying to stop all the above.

I fully appreciate what Keeping up says, as we have found similar problems [most with screws rusting through!]

so far in the last two months we have

- taken out the chimney where most of the water was coming in - this currently has many layers of plastic and tarpaulin covering it for the winter but the leak from that caused a lot of wood rot internally.

- removed all but the rear window down the port side - these where resealed with a liberal dose of clear mastic on the inside and a paintable mastic under the metal frame on the outside. Be very wary of the windows if they are the louvre type - as we had gaps in the welds of the frames.

- Again on the port side [as this was in the worst condition] we have individually removed most of the external screws, replacing with new stainless steel ones and squirting lots of mastic in the holes

- Removed the old "putty" from the roof/sides and sides/metal joint and again filled with an external flexible paintable mastic. I think on that side alone we have used 6 or more tubes - thinking of taking out shares in DowCorning.

 

The mastic was finished in late september and the other day, on a warm autumnal day, we managed to get two coats of undercoat to the portside so - hopefully that will protect it until we can do a proper paint job in the spring time.

 

As for the type of mastic - it was a bit pot luck from Screwfix - it was a DowCorning make, and for external use - and black (?!? )

 

I am trying to put together a little work diary on my website - its a bit out of date, but you can see what we are up against.

 

Good luck with your harborough!

s