Render Query

[deuce22]

Hi.

I am asking this question just out of curiosity more than anything else.

I am going to be rendering my property soon and have decided to use Parex, which has been advised by the plasterers that specialise in silicone render.

They have said that they are not going to use any stop beads to separate the top half from the bottom half. The job looks more professional having the whole wall rendered in one go and the reason most people do it is due to the fact that they cannot handle a large area in one.

Another plasterer who came to quote said he would be using stop beads to split the bottom and the top and said that they are supposed to be used for water to run off.

Can someone please tell me who is correct.

Cheers.

 

[dmplastering]

Hi.

I am asking this question just out of curiosity more than anything else.

I am going to be rendering my property soon and have decided to use Parex, which has been advised by the plasterers that specialise in silicone render.

They have said that they are not going to use any stop beads to separate the top half from the bottom half. The job looks more professional having the whole wall rendered in one go and the reason most people do it is due to the fact that they cannot handle a large area in one.

Another plasterer who came to quote said he would be using stop beads to split the bottom and the top and said that they are supposed to be used for water to run off.

Can someone please tell me who is correct.

Cheers.

first one is correct, use the stop beads along the bottom for the water to run off. I wouldnt split panels in half either

 

[Alastairreid]

There are different types of beads used for different reasons, bellcast beads used at mid point in a large gable for example is to shed the water, this has nothing to do with the ability or speed of the renderer.

Bellcast beads are also normally used at dpc level for the same reason.

Then you have expansion beads which are installed at various areas for reasons which are self explanatory.

 

[deuce22]

They are using an expansion bead on the rear of the house as it is 14m wide.

They are also using drip beads at DPC all around the property.

The Gables on the property measure 6.5m wide x 6m at the highest point, so they are pretty large.

 

[Alastairreid]

The Gables on the property measure 6.5m wide x 6m at the highest point, so they are pretty large.

Pretty standard sized gables.
They can be done in one hit without splitting with bellcast beads.

 

[roy c]

But when you look at some "large" areas that have been done without beads a lot of them tend to crack, you can notice this more on the ones that are not painted. As for the ones that are painted the cracks stay hidden for a lot longer but they will appear.!! One thing that is gauranteed is at some time in its life concrete and render will always crack....This is my own opinion of being in the game for over 30 odd years...And I walked past a building the other day that had been done in synthetic materials and it had the classic cracking to the sides of the lintols above the windows.... It would be interesting if any of you "old spreads" agree with me or not....

 

[Alastairreid]

Dont know about old Roy but ditto on the 30 odd yrs, agree totally with you on the cracking issues though less prevalent with the polymers on the market these days.
Normally for example a three storey gable we would insert a bellcast along the length at wallplate height at junction with apex, then x2 stop beads with approx 5mm gap the full height of gable mid point vertically from top of apex to dpc bellcast. And corner beads...labour saving ya know..
This would give you a total of 4 panels which of course it does make it easier for us guys but also serves an important purpose.

This type of detailing was specified during rufurb works by local authority architects, then of course if there are insulation boards to be fitted, the beads would be the deeper (much more expensive type) to accomodate the depth of board.
Travel the schemes of Glasgow or Edinburgh With either render finish or pebbledash/roughcast and you wont see any large areas of either without the necessary beads installed.

Over and out!

 

[deuce22]

I haven't got the experience you guy's have, so it's pointless me commenting on the longevity of render.

I personally prefer seeing no drip beads apart from at DPC level and if the that they are used is due to it being easier for the plasterers, then I'll continue to use these guy's as they prefer to do it this way.

I'm only talking about silicone render systems in this post, so the comments made about traditional render (cracking) are probably correct.

These guy's have been going 10 years and 80% of there work is silicone render. The plasterer that I use for internal work also advised me to use someone that specialise in it.

The size of the gables may be a standard size, but I have seen areas smaller, even Bungalows with a drip bead half way up.

It does make sense to add in beads when using traditional render, so there's less tendency for it to crack, but according to the company Parex, this stuff is flexible, so as long as you insert expansion beads where they state you won't have any issues.

Only time will tell.

Thanks for the advice.

 

[Alastairreid]

Yeah thats what i was saying earlier! a gable the size of yours will only need beads at dpc level.

Another important point while i'm here is if you are insulating its possible you may need to extend your cills and remove and re-install your svp, rainwater pipe and any other services entering the building which may interfere with the continuity of the boards.

Good luck with your job.

 

[deuce22]

I've laid a block and beam floor and all the pipes are going under the floor and out below DPC.

I've just had the windows fitted. Why do I need to have the cills extended?

 

[Alastairreid]

Depending on the thickness of the insulation boards they could bring the depth of the finished render beyond the dripline of the cills.
In our case it was 100mm boards mechanically fixed then mesh, base coat then top coat to finish.
This little lot would have brought the cills level with the finished render..therefore cill extensions were required.

As i said it may not be the case with your house just something to look out for before you start your job.

oops sorry i just re-read your post..i thought you were insulating as well

 

[deuce22]

The property has been built using the following.

100mm concrete block, 110mm cavity with 60mm insulation and then another 100mm block.

The cill is protruding 35mm and when they render 15mm thick there will be 20mm overhang.

Can you tell me what setup you have done on your property, just curious.

 

[Alastairreid]

Not my property! we contract to local authorities..the scenario with the 100mm insulation boards were post war prefabs, single block outer skin no cavity framed and gyproc. zero insulation.
These houses were designed on a limited lifespan 30yrs i think due to the post war housing shortages.
Anyway 2012 and they are still here schemes of them which all needed upgrading to modern day thermal standards.

Then of course there was the roofs, metal purlins, thats another story.

 

[deuce22]

Thanks for the explanation.

I thought it was some kind of new build system.

Thanks again for all your help.