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Today I visited site to help an experienced applicator iron out some minor application issues they were having with the K Rend K1 Silicone product. They were complaining that the material was setting slowly now the temperatures have dropped and it was also proving difficult to handle as it was tending to tear and slip down the wall when ruling off. Finally, there were small splits and holes appearing that the applicator was having to fill during scraping off which was slowing the job down further. These are not uncommon complaints with this and other products on the market so I was thankful that an applicator finally let me join them on site to investigate and find a solution.

We decided to set the job up as per the below working parameters for todays application. The aim was to eliminate the slow set times whilst tweaking current application methods to eliminate the tearing and splitting. The first thing we did was introduce an accelerator and I used a calculator to ensure that correct dosage was used along with correct amount water in the mix. It’s a common mistake to overdose accelerators which can cause machine blocking issues due to things like flash setting blocking the pipes whilst not actually speeding set times up when the material is on the wall. Cements overdosed with accelerators may not cure with the structural strength they should have as well. Overdosing accelerators is just a big waste of money! 

Substrate:

New 7nm Medium Density Blockwork.

Spray Size:

Approx 80m2 (100 bags.)

Application Specification:

1 pass direct spray application of K Rend K1 Silicone onto the substrate at 17mm then scrape finished at 15mm. K Rend Mesh applied to stress points and openings. I did suggest 2 pass application but the applicator today was keen to see if we could get 1 pass working for future reference.  

Application Weather Conditions:

Temperature was 11c at 10am rising to 14c by 1pm. Slight breeze. Overcast but dry.

Additives Used:

K Rend Accelerator at a ratio of 5l per 220l water drum. (Approx 130-150ml K Rend Accelerator per bag.)

Spray Machine Used:

PFT G4, 25m hose.

Spray Machine Water Consumption setting:

The machine was set to mix approx 6-6.2l of water per 25kg bag.

Previous Application Method:

1 pass spray to 17mm, rule with a straight edge, Open up with an I Bar after initial set and then lightly finish with a hand scraping tool. This applicator achieved excellent results using this method, some of the best I have seen whilst still having the previously described issues with product tearing and splitting working this way.

Agreed Revised Application Method:

1 pass spray to 17mm, initial level with a H Section Serrated Edge, followed by a final ruling off with a straight edge. Open up once initial set has occurred with an I Bar, followed by a light scrape.

The Process

The first thing to do was ensure the machine was running smoothly with all pressures correct. It was running like clockwork with the above water settings.

K Rend K1 Silcone was then sprayed to approx 17mm thickness in 1 pass with an under and over spray pattern as per the video. (This was against my wishes as I was suggesting 2 pass, but this applicator was stubborn!) Spraying was complete by 10.30am.

The biggest change I made to this applicators day was I suggested to use a H Section Serrated Edge levelling tool for the initial ruling off instead of just using a straight edge as these are great for removing trapped air from under the surface of the render. A serrated surface is also much easier to rule off with the straight edge as well so it should speed the ruling process up! The slow motion video above should show how easy it is to trap air when spraying. If the trapped air is not removed before levelling the surface with a straight edge the render does not get chance to properly knit together at the air pockets which may cause tearing and slippage down the wall when a straight edge is dragged across it. This obviously wastes time and causes frustration due to the need for constant reworking of the surface. The pockets of air under the surface of the render may also reveal themselves during the set or final scrape as well resulting in the need for filling holes and splits during scraping which is far from ideal.  

The H Section Serrated Edge is in action in the video below. Look closely and you may see the air pockets opening up at the surface as the render knits together. We experienced absolutely no slumping or tearing of the render when using the serrated edge, much to the applicators amazement!

The serrated surface was then ruled with still no sign of tearing or slumping and the render was then left to set.

Thanks to the correctly calculated K Rend Accelerator dosage the applicator was very pleased to see that the render was ready for opening up a mere 2.5 hours after he had finished spraying and the I Bar was brought into action at 1pm! The I Barring was quickly followed by a light scrape and a brush off. Thanks to the use of the serrated edge there was none of the holes and splits that the applicator had been having to deal with previously and the finishing of the render was much quicker.

On site for 7.30am, 100 bags applied and finished by 3.50pm! Hopefully you should see that the finished result is simply stunning! The applicator is now much happier working with the material due to the small tweaks made to his technique. The Serrated Edge is now an essential tool for all the different render products he applies! 

I've not blogged for a while, a combination of idleness and high workload getting our new website and internal systems up and running made me take my eye off the ball but an interesting debate has arisen from our recent invitation to help Alan Titchmarsh and the team on ITV's Love Your Garden NHS Special TV show.

I don't get on site much these days but the attraction of potentially getting my face on the TV made me set the alarm clock 3 hours earlier than usual and head over to site with some of the guys to "render a wall." Our brief was limited, we knew it was a freshly built wall 15-30m2 in size and we knew it needed rendering in 3 days time with only a 9 hour day to do it. Armed with this wealth of information I planned meticulously for all potential outcomes, or so I thought...

We filled the van with boxes of Renderplas beads along with K Rend bonding aids, accelerators, base coats and top coats as they were the manufacturers of choice for the Love Your Garden Team, we were ready for anything, or so we thought!

We arrived on site to damp windy conditions with temperatures of 6c, the signs were ominous. We had about 9 hours to render 30m2, including fitting the beads, not a lot of time for render to set in these conditions ready for scraping we needed to start and start now!

We got the site induction done (30 mins) and spent the next 20 minutes figuring out how we could get the van on the incredibly chaotic tight site entrance full of trades falling over each other to get unloaded. The Ritmo render spray machine and K Rend render materials were literally thrown out of the van as time pressure was mounting. One the guys was sent over to the wall to get clipping the beads whilst we went to solve the next problem. Water.

30 minutes later we had a full 200l drum of water and the Ritmo was close to sparking into life when the question, "How are we fixing the beads?" was asked.

"I brought K Rend HP12 base coat," was my sheepish answer although I was slowly coming to the realisation that we didn't have time for that to set and the lads just laughed that suggestion away

The next suggestion of galvanised nails was also met with laughter as the wall we were working on was still being built in places. Sigh.

We only had one other choice.... Instant Grab adhesive, the solvent type with a colour 50 shades or so less than red. You all know what we mean. We didn't have any, so I jumped in the van to the nearest merchant whilst they got set up. 40 minutes later the beads were fixed and the job just about ready for the application of K Rend K1 Silicone top coat render. K Rend Accelerator was definately needed!

This got me thinking, none of the methods of fixing the beads that were suggested was ideal in this scenario for these reasons:

1) Using Base Coat / Coloured Render to fix PVCu Beads.

Setting times are a problem with this one if you're in a hurry or under pressure as we all are then this causes problems, especially when you factor in that you can't mix up until the van's unloaded and all site services are available.

2) Using Galvanised Nails to fix PVCu Beads.

Some do this but you can end up with warped beads if the nails end up putting pressure on the PVCu render bead itself. Its not ideal on single skin walls either as you risk loosening the masonry with the hammer strikes. The other question is, just how galvanised are those galvanised nails?

3) Using Instant Grab Adhesive to fix PVCu Beads.

On the face of it this seems the ideal method of fixing beads. Solvent based grab adhesives stick quickly and dry in all weathers. We should strongly warn that they are not wthout their risks as they do have a small risk to marking the face of the coloured render if the oils they contain leech through to the surface. This wasn't a huge problem for us for this job as we could have corrected any issues with our Mendrend Render Repair System if it did happen but it could be a big problem for others who don't have the luxury of teams of render repair technicians available at short notice. We did end up using more adhesive than we'd like as the walls needed some, erm, straightening out.

4) Using Render Manufacturer Adhesives to fix PVCu Beads.

It looks like some render manufacturers are attempting to solve this age old problem by introducing their own bead adhesives which I welcome but they all seem to have the flaw that they need mixing on site which means time is potentially lost as nothing can be mixed until the van is unloaded and everything is set up and ready to go. Now, your average plasterers van generally looks like it's been in a car crash in the back, especially if they had a late day the day before. Getting set up and ready the next day can take a bit of time so one man is best getting the beads on whilst the other sets the van, machine or mixing gear up. These types of bead fixing adhesives definately aren't currently ideal in all circumstances either!

So, if you read this article looking for an answer on the definitive way to fix beads, I'm afraid there isn't one currently and it will all depend on the job on the day. We'd advise against using grab adhesives unless absolutely necessary due to the small risk of staining. If their use cannot be avoided try to use as little as possible and minimise exposure of the adhesive to your delicate top coat by keeping it under the bead itself. Big blobs of adhesive are a problem waiting to happen in our opinion.

Hopefully someone comes up with a safe to use quick setting pre-mixed adhesive soon and we can all get cracked on as soon as we pull up in the van! Gone are the days where I'd tinker with solving this problem myself.

The good news is, we been invited back onto the TV to work on another Love Your Garden job so we'll see what we end up using then!

If any of you have questions about this or any other articles please contact us.

Thanks for reading.

James.

After the cold spell temperatures are beginning to rise again above 5 degrees! This has got lots of people asking how does K Rend accelerator work.

K Rend Accelerator is a liquid additive used to reduce the waiting time before scraping K Rend scraped texture renders. It accelerates the curing time of K Rend scraped texture renders meaning that the render may be scraped earlier, enabling a faster completion of the job. K Rend Accelerator may be used in cold conditions to improve the scraping time (however all winter working precautions still apply).K Rend Accelerator has no effect on the appearance of the K Rend scraped texture render if the render is scraped at the correct state of readiness or hardness.

So why choose K Rend Accelerator?

- Accelerates scraped texture render curing time

- Enables fast completion of job

- Ideal for use in winter

- Has no effect on appearance

K REND BASE COATS

Standard UF Base, UF Fibre Base, HP12, HP14, HPX Base Primary coat, where required, should be applied to substrates as preparation for subsequent coats of K Rend scraped texture finishes. Thickness should be as per product specification. It is important to take special care to straighten with a darby / straight edge to ensure that the next coat is applied to uniform level. Form a light key only. If you are applying K Rend Silicone TC as a finish coat, do not form a key and leave the base coat flat and smooth. Allow 24 hours curing time before further application, unless advised otherwise, for instance it is recommended to allow 14 days curing time before the application of K Rend Silicone TC top coats to guarantee adhesion. For info on unusual substrates, seek technical advice.

Base Coat Recommended Thicknesses

4-6mm: HP12, HPX 

8-10mm: UF, UF Fibre Base

K REND SCRAPED TEXTURE

Silicone FT, Silicone Spray E Grade, K1 Spray, K1 Silicone

ONE COAT / FINISH COAT

One coat is applied directly onto block work (please seek advice from our Technical team) and must be finished to a minimum of 16mm thick to avoid ‘ghosting’. The material should be applied 18mm thick in 2 passes; the first pass 6-8mm and the second pass 12 - 14mm. (See also under Spray Application). After setting, 2mm is scraped off for a 16mm finish. If the material is being used in a two coat application the Finish Coat is applied over a K Rend Base Coat to line level, using a darby or straight edge, to a minimum thickness of 10-12mm When straightening, hollows should be filled out immediately before a skin is formed. Care should be taken to avoid small hollows, which can make it difficult to achieve a good finish. Small areas such as quoins, reveals and bands can be left with a plastic float finish. Do not polish.

Finish Coat Recommended Thicknesses

16mm: 1 Coat

10mm: 2 Coat Over base coat (Base coat recommended thicknesses above.)

SCRAPING

Scraping should take place when the render has set but not fully hardened. The exact timing varies according to weather conditions; can be anything from 4 to 36 hours after application. Typically, in moderate conditions, the render should be scraped the day after application. The render is ready for scraping when a thumb impression cannot be made but it can be marked with a thumb nail. At the correct time, the aggregate scrapes easily from the wall and does not stick to the scraping tool. Scraping should always be done lightly in a tight circular motion to produce a uniform finish. Remove only 1 - 2mm from the complete surface. All areas must be scraped at the same time.

K REND SILICONE TC

Please click here to download K Rend Silicone TC application instructions PDF.

First Coat: K Rend Basecoat 

Preparation Coat: K Rend Primer TC

Final Coat: K Rend Silicone TC

Ensure that the background is clean, level and dry with no signs of efflorescence. We recommend newly applied basecoats are allowed a minimum of 14 days to cure.

Ensure all adjacent surfaces are well protected and masked. (Windows, sills, doors, floors, glass, brickwork etc.)

Application 

Apply K Rend Primer TC (Colour matched to topcoat) by brush, roller or spray. Ensure that 24 hours drying time is allowed before the application of the topcoat.

Apply K Rend Silicone TC topcoat to the thickness of the largest grain size using a stainless steel float and allow to take up slightly. (This is only a few minutes.) The surface is then rubbed up in a circular motion using a plastic float to create a uniform texture.

Ensure that you complete full surfaces in a continuous motion without interruption. Maintain a wet edge at all times. 

To avoid run off, protect freshly applied render from rain and drying too fast. Drying times will be prolonged, sometimes quite drastically, by low temperatures and/or high humidity.

MACHINE APPLICATION

The following K Rend products can be spray machine as well as hand applied; Silicone Spray E Grade, K1 Spray, K1 Silicone, Overcoating Silicone Dash, Silicone Spray Dash, Silicone Tyrolean, Standard UF Base, UF Fibre Base, HP12; HPX Base. M-Tec spray machines are available to purchase or rent from K Rend. A technical advisory service is also available.

The use of timber cladding and elaborate wood detailing in new builds and refurbs seems to be on the increase in a big way. When wood is skillfully used in a contemporary design along with a great looking render such as those by K Rend or Parex the results can be stunning.

Unfortunately, in a lot of cases this stunning look may only be temporary as one key problem seems to be getting overlooked time and time again if the regular calls our Mendrend technical team receive are any indication.

A lot of the pressure treated timber on the market appears to be treated with a substance that is not completely water proof so when the timber gets wet the wood stain is then dragged down the wall which then pentetrates deep into any surface that is porous such as your normal cementitious render. The results can be devasting and extremely difficult to correct. We strongly advise if you are considering the use of treated wood in the design of you build that you check with your wood supplier that the treaments used in its production are completely stable in the presence of water or consider the use of an additional wood seal that makes the timber completely impervious to water.

Please call our technical team if you need any advice with the rectification of this issue.

We've specialised in repairing renders for many years now from the design and development to on-site application of our specially designed patented Mendrend range of products we have been focused on customer service as a core driver of our business.

During our time as render repair specialists prior to our focus on the supplying of materials we quickly realised that there is a key grey area when its comes to render applicators and the manufacturers warranties that are provided when renders are correctly applied. This grey area is building settlement; if a building settles (The vast majority don't but any building can.) and cracks after render is applied it tends to be the applicator who is blamed when in fact its absolutely no ones fault the issue has occurred. The applicator may then call the manufacturer in to see if the issue is covered under the warranty only to be correctly told that settlement is not covered under their standard warranty terms. This would be the case for pretty much any render system sold on the market today. 

This usually results in the applicator / builder / customer going round in circles trying to solve problem and one of them ends up having to pay to correct the issue depending on who loses the argument! 

Our no quibble crack free guarantee provided when we supply render systems is designed to solve this age old problem. We have teams of technicians who operate nationwide assisting customers and resolving disputes daily. I'll be frank we don't aim to be the absolute cheapest render supplier out there, I'll leave that to the guys who cannot provide their customers with assistance or have no idea what they are selling.  We aim to provide low competitive prices whilst providing help when needed.

We invite all our applicators to offer this guarantee to their customers and maybe offer a cheaper price without this guarantee if a cheaper supplier is available and let the customer themselves decide.

We invite all our customers looking to have their own properties rendered to strongly consider our industry leading backup service for what tends to be a small addition to the price of having the works done.

Those who have ended up actually needing repairs done have found our service to be invaluable. A simple crack which normally could have been a problem to fix suddenly becomes a simple phonecall. This service is currently implemented on large housebuilder sites such as Taylor Wimpey, Arncliffe Homes and Cyden Homes with great success.

If you have any questions about how you can provide your customers with better service please contact us.  

It's started.

The phone has rang a couple of times this week with customers a little flabbergasted that the thin coat render they applied a few days ago has washed off in the last rain shower with a slightly accusatory tone in their voice.

All I will say on this matter is that there is nothing wrong with the material when this happens, and its not unusual for customers to start flagging this issue up at this time of the year, as its the same every year. The simple fact is that some thin coat renders perform better in cold and damp conditions than others and each job needs planning accordingly.

Traditional thin coat resin based bucket renders generally depend on good air drying conditions as there's no curing process with these. If the air is constantly cold and damp they struggle to dry if not protected and can hang around for days only for a rain shower then take them off the wall in a hair curlingly frustrating fashion. They will dry in cold (5c+) air if the air is dry and crisp and the background is dry, but it may still need a good 24 hours before it is considered safe from the weather. Be careful with these at this time of year, a weather shielded scaffold and a space heater goes a long way to alleviating some of the problems cold damp weather may bring with these types of renders. 

The new mineral thin coat renders such as K Rend Mineral TC perform better in colder conditions with less risk of washing off because they cure and are much less dependent on good air drying conditions to harden. They still need to be applied on a dry background, but a bit of fog or moisture in the air won't prevent them from going off completely and drying times will be measured in hours rather than days. Temperatures still need to be a minimum of 5c on a rising thermometer. This is an excellent winter alternative to a traditional thin coat render if you have a job that needs to be done!

If you have any questions or need advice, please contact us!

We have briefly mentioned in previous blog articles some of the benefits and reasons you might want use an external render system, but it is worth further elaborating on these points and more as to why rendering an external wall is beneficial to a property.

Improve the external appearance of a property

There’s no denying that applying a render system to an old, tired-looking building will transform its appearance – making it look modern and more visually appealing.  Local authorities will often use render when renovating their properties for this reason.

This aesthetic improvement can be beneficial in multiple ways – if you live in the property - it makes your home look nice. If you looking at selling a property, it can make it look more visually appealing to potential buyers. 

From a wide range of colours, to a huge selection of textures and finishes, there are a wealth of possibilities available when rendering a house.

Increase the thermal efficiency of walls

Some renders – like the K Rend Silicone Thin Coat range – can be used as part of an External Wall Insulation System. While most render systems themselves are not classed as insulating (though they do provide a small amount of innate insulation), when used as part of an EWI system they can help increase the thermal efficiency of walls and reduce heating bills – not to mention the other benefits featured in this article.

Weatherproofing

External walls that are in a poor condition can lead to the ingress of water and external debris which will worsen if left untreated. The use of a render system on an external wall forming a barrier, protecting a building from the elements. These renders incorporate water repellent technology, protecting against water whilst still allowing the substrate to breathe.

If you need help with applying render or you would like to know more about the benefits of render, contact our experts today.

Render systems are available in all sorts of colours, styles, finishes and textures and whilst they all vastly improve the appearance of a building, their suitability and appropriateness vary from factors such as the building substrate to planning regulations of the local authority.

What types of render texture finishes are possible?

Each manufacturer has renders with different finishes, and the look you wish to achieve will influence the render system used.

Textured, Smooth, Scraped and even more unique finishes such as brick effects or ashlar detailing are achieved via a combination of the application method and the finishing tool used.

How are different texture finishes achieved?

Standard renders usually have 3 categories of finishes - scraped, smoothed and textured – each with their own subtle variances. For example, Parex Monorex can be scraped to achieve a fine or medium finish. 

Scraped texture finishes are achieved by scraping the render with a scraping tool before the render has set hard whereas using a trowel or float will result in a smooth-looking finish.

Applying the render using a spray machine will give a far more pronounced texture finish, similar to tyrolean and roughcast.

There are also more technical and specialist finishes such as pebble dash where an aggregate is thrown onto a wet receiver; and brick or ashlar effects, where a pattern is cut into wet render to give it the appearance of real brickwork. 

Guidance on choosing the best texture finish

For advice on achieving the right texture finish, or if you would like guidance on choosing a texture finish, contact our experts who are always ready to help.

The result of a well-applied render system is a fantastic looking finish, designed to give old and tired-looking exteriors a new lease of life.

However, this is only true if the chosen render system - such as K Rend - is applied correctly. Incorrect application can result in the failure of the render system, requiring it be replaced. One of the main factors of a poor quality K Rend render system is due to the applicator not having sufficient knowledge of how to apply K Rend.

Always Follow Manufacturer Guidelines

Rendering an exterior surface is a technical task but its payoffs are well worth it – a fantastic looking exterior finish with additional benefits such as weatherproofing and improving the visual appearance of a tired, old building.

People may be put off using products such as k rend insulated render systems due to the horror stories that have come about due to applications performed incorrectly either from lack of experience or failure to follow manufacturer guidelines. If applied correctly, problems like the infamous Curse of "Halo Ring" can be easily avoided.

Different Methods Yield Different Results

The application of k render systems affects their appearance, both in how it is applied and how it is scraped – just take a look at our blog post on Why You Should Always Provide a Customer Test Panel. In order to achieve the best results, it is essential that the render is applied in accordance with the official K Rend instructions.

Use an Expert for Expert Results

Our qualified technicians are experts in applying K Rend and can help rectify any mistakes or issues that occurred during a previous poor application. Contact us today for help and advice on k rend application.