Open Association of Landscape Industries
Weed supressing Membrane
Advice anyone pls...
About four months ago we completed a dig off, laid a permeable membrane and then covered with limestone chippings, ( other works were carried out at the same time), within a month weeds appeared<( we duly removed these), now the customer is asking for a remedy as weeds /grass has reappeared. My dilemma is this, do I one the one hand state that works were carried out as per quote and therefore maintenance of the area is down to them or do I remove all gravel and double up the membrane(or similiar, suggestions welcome). Any thoughts ideas much appreciated.... p.s....the job was a very poor earner as I dropped the price on the promise of additional work at their additional properties, suprisingly this was never mentioned after we completed the work.
Replies to This Discussion
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PRO MemberPermalink Reply by Claire Brown on -
I agree with Gaynor, - and I never use the thin grade of membrane as it is a waste of time, - you need Mypex or equivalent- However I would let your client know that weeds can and will grow in gravel, particularly if it is in an area where mud is traipsed across on shoes/boots, -so although a thick membrane will prevent perennial weeds coming through from underneath, they won't stop annual weeds from growing in the membrane.
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Permalink Reply by Paving & Landscape Company Ltd on -
I don't advocate walking on a weed membrane, since sharp stones will penetrate through the barrier. It's purely ornamental and not for regular traffic.
I've seen some awful examples of membrane laid and used on drives, paths etc. Certain chippings are terrible like Cotswold chippings as they crumble easily and provide perfect growing medium for weeds to take hold.
If the membrane you laid is getting regular foot traffic, then in my opinion the spec you laid to is flawed.
If it's not walked on much, then the gravel needs to be stripped back. Another layer of better quality weed membrane put down along with a thick ( 50mm ) layer of clean non-absorbent gravel.
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Permalink Reply by Geoff Norfolk on -
Why not spray the area with a suitable herbicide such as Pistol which should kill off any weeds and prevent new ones growing for months. Are the weeds actually growing through the membrane or in the chippings themselves? In my experience, you always seem to get some weeds that grow in the gravel etc but at least they pull up easily and there's not many of them.
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Permalink Reply by phil smith yewtreelandscapes.com on
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check to see if the weeds are growing through the membrane or growing in the gravel, if they are coming through the membrane then it is poor qualitey membrane, but if the weeds are growing on top in the chippingsthen it is down to the customer to pull the weeds out their self.
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Permalink Reply by Michael Gurney on -
Do they or have they done any gardening or maintenance since you finished? i had this and found the customer had not touched a thing and called me back after 6 months with weeds growing!. just an idea.
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Permalink Reply by Steve Boyle on -
Hmmm, many thanks for all the replies, some obvious and also interesting points, i am suspecting growth on top of the membrane. A reply for Michael, no they havent carried out any maintenance,( i believe they are chasing the ultimate totally maintenance free effect......). Anyway Ive a meeting with them on Monday so I will keep you posted....many thanks...Steve
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Permalink Reply by duncan ross on -
The dangers of doing cheap work always come back to haunt you, and funnily enough its the poor paying customers that want a silk purse from a pigs ear (old saying - but good). Sorry to hear your problem, but my opinion would be it is your professional duty to determine the cause of the problem & suggest solutions. Ring them immediately & say you need to have a look at it. Have a thorough inspection. If the weed membrane is torn & its a result of misuse, it will need to be replaced & you will have to negotiate who is to pay. If they clearly have been or dogs have been walking all over it & you have applied it as a weed suppresant only you are not at fault. The most likely cause is weeds growing in the surface of the chippings. These will not establish themselves as their roots will not be able to make contact with the soil. Point out that it is a weed suppresant & not a 100% weed free solution. My advice would be to remain professional and friendly at all times, and if that means popping back round for 10 mins to pull a few weeds at a time that suits you, so what, it provides you with the opportunity to ask them, "when are we going to do this other work then", afterall they were chheky enough to tempt you in the first place with extra work. You may not get the extra work if it ever existed, but you can hold your head up & know you have done your job, they will repect you for that. Also that polypropylene weave is rubbish & frays, use a fabric like plant-x, its not that much more & wears better. Good luck.
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PRO MemberPermalink Reply by Mick Gammage on -
there is a massive difference between a weed suppressing membrane and a geotextile membrane which is what you would lay on top of the subsoil or clay prior to laying a granular sub base what the limestone chipping would then be laid on top of.
to lay a thin weed suppressing membrane on top of the soil, sub soil, or clay and lay a thin layer of limestone chipping is a waste of time and will not last 5 minutes and when it get wet it will just tear apart.
a geotextile membrane on the other hand is not crap at all and serves the purpose for what its designed for, to prevent the intermixing of the sub soil or clay and the hardcore sub base yet still permits water to flow freely which is what should of been used in the first place and is available from most builders merchants either by the full roll 100 metres X 4 metres wide or cut to the desired length required.
you also need to overlap the membrane onto each other by at least 300mm, if the weed suppressing membrane you laid was just butted together then this would also cause problems with weeds.
you also mentioned that grass is appearing, did you not remove the turf before laying the membrane ?
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Permalink Reply by John Mulholland on -
Hi
From experience/observations of constructing this type of landscape areas I would suggest that any Geo-textile material that you can push a match stick through the weave, roots will find/push their way through also. The material I found best was 'advantage 1000' about £150 for a 4.5m x100m roll. We tried similar usually cheaper products but they were not as good as they had the open weave /matchstick problem, were made of plastic, did not cut neatly etc
If possible apply suitable herbicide to area a week or two before laying geo-textile. ( with the above product you may find you do not need to perform this step but would recommend that its done anyway)
If not possible to remove sharp rough object which may burst the Geo-textile, mask/cover problem area with sand or smoother aggregate or bury offending piece.
Ensure a good overlap of Geo-textile edges especially if ground is uneven/on a slope, we found that 50 cm overlap was not excessive especially if the area was to be walked on/planted (foot traffic moves the fabric)
Before applying aggregate remove (use blower or brush) the excess soils that has fallen on top of geotextyle during planting operations or off footwear.
The minimum depth of the aggregate should be based on getting at least three preferably 5 layers of aggregates on top of one another (see attachment). The idea being that no light will penetrate the aggregate to germinate seedlings lying on surface.
The aggregate keeps moisture levels in as does the geo-textyle add some soil/seeds from the sole of your boot and you have perfect growing condition.
The Geo-textile is used as a barrier to stop the soil and aggregate layers mixing reducing the need for topping up the aggregate as it is mixed to the soil. Though in saying that the Geo-textile above is certainly tough enough to resist root penetration of most plants.
Maintenance on sites prepared this way has been spot treatment/application of herbicide once twice a year or hand pull the lightly rooted weeds that have managed to germinate usually around or in the planted plants root ball where aggregate is not deep enough to exclude light
Apologies if this sounds long winded and graphics pretty basic in attachment.
Just thought I would put my tuppence worth in
Cheers
John
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Aggregate depth.doc, 32 KB
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Permalink Reply by ken stewart on -
i only ever use terram over a mot base
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PRO MemberPermalink Reply by Phil Voice on -
Some good advice here.
I have to agree that geotextile is best for suppressing pernicious weeds and I'd steer clear of any thin weed matting/membrane.
Gravel/stone chippings is a great seedbed when debris and organic matter collects on top.
Thinking of the future, it's worth writing a specification and sending terms and conditions next time you have a job of this nature.
If you are able to educate and manage the expectations of your client to the disadvantages (and this applies to all jobs) of a certain method and warn of likely scenarios under certain conditions, you will cover yourself when it comes to remdual work.
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Permalink Reply by David Channon on -
I'd be inclined to investigate a small area and determine whether its penetration or seed germination.
It has been a very warm autumn.
If it is seeding, I'd point it out to him and probably give him a spray and walk away.
If it is growing through, it is down to you loss or not. Learn from it.
FWIW, there's no membrane that I know of that will resist Horsetail or Japanese Knotweed so look very carefully when you do a site survey.
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