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Posted: Wed May 07, 2008 10:14 pm
by Type1
I'm landscaping a garden with disabled access in mind. One of the kids in the house will want to use a motorised wheelchair some of the time but other times, his parents may carry him. We have had to compromise on the gradient of one of the slopes as the garden is not wide enough to make a 1:20 so we have a 7m run that is 1:8 and a 12m run that is 1:20. We would like to chose blocks that will offer the best grip on the steeper slope if the child was being carried. I've seen some tumbled concrete that looks good (colour and style) but I don't know how it would be for grip in the wet? I was also wondering if there are blocks that are more resistant to moss and slime than others? Any ideas would be much appreciated.
Best regards,
Type1
Posted: Wed May 07, 2008 11:36 pm
by lutonlagerlout
1:8 is way too steep for a wheelchair,it used to be 1:15 minimun with 1.5m rest places every 5 m,anyway of crisscrossing the gradients
i have done this type of stuff and it can work out expensive with retaining walls etc
tactile slabs offer plenty of grip,you know the council ones with 5mm ridges on them
LLL
Posted: Thu May 08, 2008 7:31 am
by Type1
Thanks for your reply LutonLagerLout. We're not too worried about the 1:8 slope as the electric wheelchair can manage it fine (the little boy has no use of his left arm anyhow, so a manual wheelchair is not an option).
I don't know the blocks you mean but I'll look them up on the net. Any views on other blocks - especially tumbled concrete - these are the ones that I would really like to use but I don't know how suitable they are...
All the best - Type1
Posted: Thu May 08, 2008 10:16 am
by Rich H
Tumbled blocks don't offer anymore grip than standard blocks. They still have a flat profile. Search the net for 'tactile paving' and you should find something suitable.
Posted: Thu May 08, 2008 12:13 pm
by David Sarti
There will be other braned alternatives I'm sure but Marshalls have two surface textures which are very 'grippy'. There's a shotblasted finish on a granite block paver (Mistral) and a washed surface on a face-mix product (La Linia). Neither are tumbled but - as said above - that's probably not your best option in any case.
Edited By David Sarti on 1210245333
Posted: Thu May 08, 2008 8:47 pm
by Tony McC
Generally speaking, the vast majority of concrete block pavers produced by the quality manufacturers have excellent 'grippiness'. The correct technical term is Slip Resistance Value (SRV) and all of the quality manufacturers can provide info on the SRV of their various products.
While textured products, such as those mentioned by David Sarti, will have higher-than-average SRVs, the 'everyday' blocks that cost much less will have perfectly adequate SRVs.
The Paving industry traditionally measures SRV using the "Pendulum Test" which produces a number in the range 1-100. the higher the number, the more 'slip-resistant' is the surface. Any value over 35 is considered 'satisfactory' while a value of 65 or more is rated "excellent". Most concrete pavers have values in the 55-75 region.
Surface slipperiness is a science in itself, and the academics have a wide range of tests, comparisons of wet and dry surfaces, values for "micro-roughness", and a whole host of other measures that are probably more readily applied to internal flooring and tiling rather than paving, but the general principle is the same: some surfaces are slippier than others. Unsealed concrete block pavers are not usually regraded as slippery.
Posted: Thu May 08, 2008 8:59 pm
by Type1
Thanks to everyone who has offered advice. I found Tony's advice about the SRV very helpful as it gives me a way to compare products.
One thing I forgot to mention in my original posting was that the slope is under an apple tree on one side and a stand of Leylandii on the other - so there is a problem with organic matter dropping from both sides. I realise that there is some sort of balance to be struck between texture for grip and trapping organic matter and encouraging moss... Is the answer just to pressure-wash the surface regularly or are there blocks that are particularly suitable for this sort of installation?
Best regards
Type1
Posted: Thu May 08, 2008 9:42 pm
by Tony McC
Avoid textured surfaces - they make cleaning that much more difficult (and necessary!)
Find a nice, simple, plain block.
Posted: Thu May 08, 2008 10:24 pm
by lutonlagerlout
type 1 wroteso there is a problem with organic matter dropping from both sides.
simple solution: a yard broom :;):
if they are going to get dirty easily ,i still think pressed 600 by 600 "council" slabs would work best
lot easier to clean
LLL