polytunnel construction.

[cornish wood burner]

Plastic is always fresh from the suppliers but I wonder how long it has been sat on there roll before they have cut it off. My suspicion is that it is to sharp a fold as on the 40 mtr tunnels we always unroll the same way and have noticed the splitting starts from the end that was nearest to the centre of the roll. The last tunnel where splits occurred was the most noticeable with 2 folds splitting at different points on the first 20 mtrs the remaining 20 mtrs absolutely perfect and would have lasted at least another 3-5 years.

Perfectly still day today. Bet you cant guess what me and the other half are upto today.

You will have earnt your money today then. 5mph at work so we should have done one. Short staffed and lot of other things going on so no time unfortunately.

Would yours be single span with the polythene dug in? Still a lot of work even if it is.

 

When we bought visqueen it only came in standard lengths and the supplier didnt roll it. It came from further afield and might have been in a roll for a long time. Your supplier may be different but if he only offers standard lengths chances are he just buys a number of standard length rolls and puts them on his shelf and until someone wants that length. Worth enquiring I would think and if that's the case who knows how old it is.

It might have changed now but visqueen used to be supplied in very neat but tight rolls which could cause too sharp a fold.

[renewablejohn]

You will have earnt your money today then. 5mph at work so we should have done one. Short staffed and lot of other things going on so no time unfortunately.

Would yours be single span with the polythene dug in? Still a lot of work even if it is.

 

When we bought visqueen it only came in standard lengths and the supplier didnt roll it. It came from further afield and might have been in a roll for a long time. Your supplier may be different but if he only offers standard lengths chances are he just buys a number of standard length rolls and puts them on his shelf and until someone wants that length. Worth enquiring I would think and if that's the case who knows how old it is.

It might have changed now but visqueen used to be supplied in very neat but tight rolls which could cause too sharp a fold.

 

This one only a little single span baby on wooden side rails the only complication the incorporation of a shade sheet on the first 4 bays. Took us 2 hours to put on and 4 hours to fasten down the sides. Lengthways will be fastened tomorrow leaving it with weights on overnight.

 

Forecast another good day tomorrow so you have no excuse for getting one done.

Edited August 7, 2015 by renewablejohn

[cornish wood burner]

This one only a little single span baby on wooden side rails the only complication the incorporation of a shade sheet on the first 4 bays. Took us 2 hours to put on and 4 hours to fasten down the sides. Lengthways will be fastened tomorrow leaving it with weights on overnight.

 

Forecast another good day tomorrow so you have no excuse for getting one done.

 

I would but didn't see the forecast, tunnel not prepared, have to take the dog to the vet, car has a puncture and its Saturday and my guys will have run and hidden and I wont be able to contact them. That's my story anyway.

Our recovering approach is very different to yours

Pull poly over, align with ridge bar, nail one 2.4m batten one end,

go to the other, pull like demons and batten that end.

Work evenly up each side starting one batten in from the end, finally finish sides and ends to complete corners.

Edited August 7, 2015 by cornish wood burner

[renewablejohn]

I would but didn't see the forecast, tunnel not prepared, have to take the dog to the vet, car has a puncture and its Saturday and my guys will have run and hidden and I wont be able to contact them. That's my story anyway.

Our recovering approach is very different to yours

Pull poly over, align with ridge bar, nail one 2.4m batten one end,

go to the other, pull like demons and batten that end.

Work evenly up each side starting one batten in from the end, finally finish sides and ends to complete corners.

 

I think the difference is there is only 2 of use so we have to let gravity do the work whilst keeping the sides secure so that the wind cannot get underneath it.

 

Have experimented this time with a doorless end with plastic wrapped around end bar and tensioned to first bar. Looks good but time will tell. I dont get on well with doorways and forklifts they never seem to be wide enough or high enough so hopefully this is the solution.

Edited August 8, 2015 by renewablejohn

[Peter]

Visqueen lumisol diffuse is what I put on our tunnel. Seems ok so far, first season with it though.

[cornish wood burner]

I think the difference is there is only 2 of use so we have to let gravity do the work whilst keeping the sides secure so that the wind cannot get underneath it.

 

Have experimented this time with a doorless end with plastic wrapped around end bar and tensioned to first bar. Looks good but time will tell. I dont get on well with doorways and forklifts they never seem to be wide enough or high enough so hopefully this is the solution.

I think you have done very well if only two of you. It sound like a straight sided higher tunnel would suit you but of course higher means more wind and harder to reach everything. We often roll in temporary battens to hold against the wind. We stop a roll short and leave the nail head out a little.

If I understand correctly what you've done, it will put more longitudinal strain on the end hoop so I hope your ridge bar is fixed well to it. Also if you haven't braces from half way

up the hoop to the ground inside it might pay to fit some. Should give you a nice big door

though.

It would be interesting whether your supplier has a jumbo roll or is supplied with small

rolls if you can find out. Might even be the cause of your splitting problem if rolls are old

Edited August 8, 2015 by cornish wood burner

[renewablejohn]

I think you have done very well if only two of you. It sound like a straight sided higher tunnel would suit you but of course higher means more wind and harder to reach everything. We often roll in temporary battens to hold against the wind. We stop a roll short and leave the nail head out a little.

If I understand correctly what you've done, it will put more longitudinal strain on the end hoop so I hope your ridge bar is fixed well to it. Also if you haven't braces from half way

up the hoop to the ground inside it might pay to fit some. Should give you a nice big door

though.

It would be interesting whether your supplier has a jumbo roll or is supplied with small

rolls if you can find out. Might even be the cause of your splitting problem if rolls are old

 

End hoops are all braced so should not be a problem.

 

As for plastic it is Jumbo rolls they use and reroll to the cut length requested. I think its the rerolling which is the problem as its the centre core of the roll which splits first.

 

I have one straight sided and I do prefer them but they dont come up for sale very often and I dont buy new.

Edited August 8, 2015 by renewablejohn

[cornish wood burner]

End hoops are all braced so should not be a problem.

 

As for plastic it is Jumbo rolls they use and reroll to the cut length requested. I think its the rerolling which is the problem as its the centre core of the roll which splits first.

 

I have one straight sided and I do prefer them but they dont come up for sale very often and I dont buy new.

 

Sounds like they may be rolling too tight or doing something wrong then.

Depending on a lot of things we might be taking down 3x 40 metres and 2 x 22 metres of straight sided multispan. If it goes ahead in the next few years I will let you know.

[renewablejohn]

Sounds like they may be rolling too tight or doing something wrong then.

Depending on a lot of things we might be taking down 3x 40 metres and 2 x 22 metres of straight sided multispan. If it goes ahead in the next few years I will let you know.

 

Would certainly be interested as it makes quite a difference in storage capacity. I can get 100 IBC's in my 25 mtr normal polytunnel whereas the straight sided of the same length holds 150.

[renewablejohn]

Visqueen lumisol diffuse is what I put on our tunnel. Seems ok so far, first season with it though.

 

Thats what I put on this time last year on a 40 mtr tunnel and its already splitting in 2 places on the folds. Once the guy from visqueen has inspected it will be repaired with trans tape both internally and externally.