Blog

What is Render?

Rendering is the process of applying one coat or several coats of cement on external wall

s, giving a whole new appearance and potential to your building.

Typically made up of cement, sand, and lime, render can be applied to a range of substrates, and protects a building from natural elements such as rain, while allowing the building to breathe and shift, as necessary.

There are a range of different types of render, and the performance of each varies based on the substrate it is applied to, and the condition of the building beneath it. Ultimately, render can be used on most buildings, and can give it a very modern aesthetic, while protecting from weather and improving the fire safety rating of the building!

The main purpose of rendering is to improve the appearance of the building, but it has a variety of benefits that encourage people to render their homes and properties.

Benefits of render:

Render is durable, allowing a water –repellent finish, protecting the building from attack by the weather, be that sun, wind, rain, snow, and even damp patches inside the building.

Despite being durable, render is flexible, allowing the building to breathe beneath it while it protects from outside elements. This is important, as a building often shifts, and the render allows that without cracks or fissures occurring.

While it is possible that cracks may occur, a particularly good thing about render is that it can be repaired. Rendit offer Mendrend, which allows your renderer to fill these cracks, reverting your render back to its original glory.

Render offers a long lasting, permanent aesthetic to your home, and with a range of through-coloured renders to choose from, you never need to pick up the paintbrush to give your home that perfect colour you desire. Render keeps your home looking better for longer!

Common Render Questions:

There are so many renders, which do I choose?

It can be hard to choose which render will be best for your home. Rendit explains the different types of renders here. Alternatively, you can take a look at our Approved Renderers site, where you can find a renderer near you, and they will be able to consult and give you a quote.

What is the difference between Rendering and Plastering?

Rendering and plastering are often performed using similar products and techniques, however the term rendering applies to the use of these materials on exterior walls, whereas plastering refers to the use of these materials on interior walls.

What colour does render come in?

It comes in a range of colours, depending on your chosen brand. Often colours can range from anywhere between 10 variations and 48 variations, giving you the freedom to choose.

How long will render last?

Render, when applied correctly, should last for twenty to thirty years, if not for the lifetime of the building. Regular cleaning and fixing cracks can help extend this time.

Can I DIY this?

For a professional finish, the best thing to do is to hire a professional renderer. This way you can have a worry-free experience, and over the years, the render will pay for itself in preservation of your home, and savings on heating, given the insulation it offers. Find an Approved Renderer here.

There are many different types of render available in the market today and you as a consumer have to decide what type of Render System to purchase. Whether it be to replace the current render or to install a new render, it’s important to understand the differences between these Render Systems.

In this Blog, we will cover the five different types of render available and each of their properties so you can decide which is the best for your needs.

1. Acrylic

Acrylic render is typically made by adding acrylic resin to the render system. This makes the render gain various qualities from the acrylic, which include water resistance and flexibility, thus making it less likely to crack.

However, this makes acrylic render less environmentally friendly and reduces breathability for your walls, this can create issues with damp.

2. Cement

Cement render is made by mixing sand and cement to make a mortar, this is then applied to a wall to create a flat covering. Cement is one of the most basic and traditional types of render which when dry, creates a grey cement colour which can then be painted. However, a pigment could be added to the mortar to give the render its own colour when applied.

Cement render is very simple and cheap however, it doesn’t look nice, last long and isn’t weather resistant.

3. Lime

Lime render is made using lime and sand to create a mortar. The lime makes the render less likely to crack, It also adds a natural quality to the finished look.

Opposing Acrylic render, Lime render is relatively environmentally friendly and also much more durable than cement render. The main negative to this type of render is that it costs quite a lot alongside it taking a long while to apply.

4. Pebble Dash

Pebble Dash render is made by adding gravel, pebbles, shells or flint to a cement or lime mortar. These can be added to the mixture or to the wall after mortar application.

For both methods, pebble dash render adds a rough texture to a wall and adds a lot of weather protection to a wall. The best thing about this unique render is that it’s relatively cheap. However, it can make a wall look dated when worn.

5. Silicone

A lot like acrylic render, silicone render is made with cement and silicone. This creates a water-resistant render which stays breathable and needs minimal maintenance.

Although, Silicone render is really not eco-friendly and costs a considerable amount more than other alternatives.

If you would like your house rendered, Find an approved renderer near you today

Why is batch to batch consistency an issue? What are the pitfalls of ordering little and often? Is ordering small quantities just an added cost? Is ordering more than enough better than just enough? Surely a “British Standard” colour is the same wherever I buy it from or whoever produces it? How do I avoid creating a moving target? These are all related to the same topic and the net results being the same, a potential problem; A colour difference.

All thin coat renders are a blend of constituent parts, each part made independently and joined together at least once, to create a coating. Some ingredients are joined together to make a part that goes in to making another part and so-on. Every time one component is produced, it is manufactured to a tolerance. By definition, where there is a tolerance there is the opportunity for a variance, this in turn can lead to inconsistencies and in render terms it can lead to appearance differences.

The moment you order or require additional render for an existing job, by definition it is a new product/batch of render. Yes, the same formulation may be used but if the constituent parts are slightly different tolerance the end result will be slightly different. You may have noticed that wall-paper has a batch number on every roll and that you need wall-paper from the same batch to ensure the patterns align correctly. The same wall-paper producer, producing the same pattern will recommend the use of the same batch. If the wall paper rolls are not from the same batch the patterns will not usually match up, even if in only one small segment of an edge. This is because the one of the constituent parts in the same factory (paper, inks, printing or cutting machinery) is different from the alternative batch. The same can be said for renders, particularly thin coat renders.

How can these situations be avoided? It is not as straightforward as ordering a specific RAL/BS level and be assured it is going to be the same colour. Every render manufacturer has their “own version” of a shade which falls within “their tolerance” of the colour. If you request the same colour from the same manufacturer, the colour may be slightly different due to the forementioned tolerances in the constituent parts. The only way to be sure of getting a consistent thin coat render colour throughout is to make one batch of the right size. Assuming this is thoroughly mixed it will ensure that the first tub is the same as the last tub in this batch. Any thin coat render produced in any other way could have variations, however small. As tint and binder stocks rotate, a variance one way or another may lead to changes, most are so small that they are un-noticeable. These changes can magnify over time as more and more batches are produced. What are the answers? For most manufacturers it is not commercially viable to produce single render batch in quantities of less than 1000kg and so the chances of every tub being exactly the same colour is limited. So, the next best thing is to order enough thin coat render to complete the job in hand as this will at least remove one link from in terms of batch-to-batch risk. When ordering a tub or two at a time, the risk is increased due to the “turn-over” of constituent parts over a prolonged period of time. Better to have 10 x 25kg tubs made at the same time in comparison to 1 x 25kg tub made every week. If you for whatever reason you need additional thin coat render to match an existing job, how do you best avoid batch to batch variances? If you haven’t ordered enough render initially, do not use every last drop of material before starting the next tub, use the original tubs and keep topping-it-up to blend any variances as it is used. Some render manufacturers will supply a batch number and this may relate to the formulation used or possibly a retained swatch of render from that batch. If further thin coat render is required, the batch number can be given and the supplier can produce to the same formulation and check the colour and sheen against the retained panel. If the same formulation is used, the thin coat render supplied may fall within “their tolerance”, which may be visibly noticeable to the eye.  Will a supplier charge you for matching? Arguably yes, arguably no. Should a render company be able to produce the same colour every time? In theory yes, in reality not every time! The need to order enough render at the beginning of the job will invariably come back to haunt you if you under budget on quantity. Hopefully this will give an insight into batch-to-batch variances and demonstrates the benefits of ordering the right amount of thin coat render for every job. This scenario is typical for all thin coat render producers, anyone who mixes thin coat render has the same issue.

A very common misconception is “colour standards”, by definition a “standard” is “something used as a, norm, or model in comparative evaluations”. When this is used in paint or render production it is quickly followed by “tolerance” defined as “an allowable amount of variation of a specified quantity”. A quick explanation of colour before getting in too deep, colours can be decoded and given a numerical position on a colour graph. If you imagine a cross on a clock face, with Yellow at 6 o’clock, opposite yellow is blue at 12 o’clock, Red at 3 o’clock and Green at 9 o’clock, every colour falls somewhere on the clock . That same colour when produced can be measured and as long as it falls within its manufacturers tolerance it is deemed a good commercial match. The problems begin when different manufacturers have different tolerances or the same company produces one batch within tolerance slightly on the “yellow” side of their “standard” and the next batch on the “blue” side of the tolerance, visible change may be negligible or noticeable. The next batch may be “bluer” again and so the colour drifts batch on batch and the potential for change increases.

This blog is not designed to give a clear-all solution, it has been produced to give a wart and all insight into paint production. Batch-to-batch consistency is resultant on the pigments, binders, dispensing equipment and critically quality control. If the pigments and

binders are not very tightly controlled; the dispensing of the formulation counts for very little in terms of consistency. Many car paints cost significantly more than industrial or domestic paints, this is largely born from the quality control of the pigments and binders. Hence why there may be more than two dozen variants of “Arctic” white, this is where the shade has moved over time in a car production plant.

Long story short, if you are unsure please contact us!

Our Rendit Approved Renderer scheme is causing a stir in the marketplace and understandably so. The presence of clearly exasperated competitors questioning its very existence on our social media only goes to show the strength of offer! It is an unusual offering that offers tangible benefits to all involved including us as a supplier, applicators, manufacturers and customers!

So, why and how does it exist?

Rendit was formed as a company in 1994 and for a lot of years only specialised in the formulation and application of the Mendrend Render Repair system to help applicators and end users repair common issues that occur day to day. These issues are generally very tricky to correct and the next 20 years or so were spent perfecting the art of render repair through constant advancements in product design which eventually became perfected and patented. Our company operations for a lot of years were extremely limited and small in scale but with regards the Rendit Approved Renderers scheme were especially important as we developed a level of expertise few have been able to replicate. As we all know experience can only be earned, never taken!

Around 6-7 years ago Rendit moved heavily into the supply of render systems as well as still specialising in technical repairs of the same systems. In hindsight this was a natural progression as being able to offer a high level of technical support and expertise in all aspects of the rendering process is something we feel that is missing from the marketplace. The relationship between supplier, manufacturer and applicator can be fractured with regards customer support and the service available so it is handy to be able to bring it all together in one coherent and seamless package with multiple manufacturers, which hopefully a lot of our customers appreciate.

The Rendit Approved Applicators scheme is designed to further unify the relationship between customer, supplier, applicator and manufacturer as we look to tie the expertise of all involved together. Expert applicators can now utilise the expertise of manufacturers along with our own experience in solving the day-to-day problems that can occur. Our own 5 Year Crack Free Guarantee closes the door on the last but common problem faced day to day by applicators where generally there has traditionally been little protection afforded by manufacturer warranties due to the nature of the issue.

As a Rendit Approved Renderer you can obtain benefits not available at your average supplier, these include:

1. Free Google marketing on one of the industries busiest websites, customers can search by postcode and automatically be put in touch with their nearest Rendit Approved Renderer. Our marketing teams are currently tasked with maximising enquiries for applicators through the scheme. These will not just be any enquiries as we are looking for customers who want quality workmanship with the backup of warranties.

2. Free site surveys where our team will liaise with manufacturers to obtain the most suitable warrantied specifications from multiple BBA tested manufacturers for you and your customers.

3. A free 5 Year Crack Guarantee which will be provided by Rendit in addition to your Manufacturer warranty. We would strongly advise everyone reads the information on this here as it is truely an exceptional offering: Crack Free Guarantee | RENDIT 

4. Priority access to on-site support teams with a level of expertise simply not available anywhere else to help to take the hassle out of day-to-day problems that may occur.

The beauty of the scheme is that we do not even want you to change your existing supplier, (Although it would be nice!) become Rendit Approved and just work with us with any enquiries you receive through the scheme and we think that you could be surprised!

If you want to become Rendit Approved visit our website and apply here: The Home of Approved Render Companies | Rendit

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.