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Frequently Asked Questions

We are very happy to answer any questions that you may have.  If you don't find the answers here, please telephone or email us and we'll do our best to help.

Do we need specialist plans to design an R-WALL build?

No. R-WALL does not require specialist plans or consideration. The simplicity and versatility of R-WALL means it can build anything accurately. Unlike other ICF systems R-WALL is not modular. Modularity is restrictive and would require specialist plans and consideration. Therefore at design stage R-WALL offers a simple solution, keeping costs to a minimum.  R-WALL can be used to construct any builds off plans including those created for other types of construction. 

Are there any design limitations with R-WALL?

No. R-WALL due to its "non-modular" design offers immense flexibility, unlike other ICF systems. With just 4 basic components R-WALL can build pretty much any structure, from curves to stepped walls, corbels, retaining walls, basements, ponds! The list goes on. In fact, reinforced concrete provides architects and engineers with increased design options through the use of retaining structures and large cantilevers. Added to this is the ability to maximise adverse and difficult to develop sites, because of the lightweight, robust and versatile nature of R-WALL structures.

Is there any flexibility to make changes as you build?

Yes.  One of the major benefits of R-WALL is the ability to build independent walls.  Sometimes, as a result of design or engineering changes perhaps, it is not possible to finish a section of wall.  With other ICF systems work has to stop because a course has to be completed at a time. R-WALL allows one to stop along a section of wall, continue building upwards and then join the wall with the R-Rail at a later point. This has proved to be beneficial on several occasions. It also means that large panels can be built independently on a jig, lifted into place and joined with connector strips. In fact, on some projects this method is the preferred construction choice, resulting in excellent build speeds.

How do you build the walls?

A course of starter pieces are secured to the concrete footings or slab and then R-Rails are inserted. A 300mm R-Board panel is placed into the rails.  More rails are put on top of the panels and then another course is constructed.  Alignment props are used after 3 courses.  Plumb corners result in true formwork and the fact that we are able to pour up to 3.3 meters at a time leaves plenty of time to align the wet concrete for completely upright and straight walls.

How do you get the concrete into the walls?

Easy! Concrete placement is usually achieved with a boom pump through a hose reduced down to a diameter of 75mm. This gives us excellent control of the flow of concrete and minimises the pressure on the formwork.  On occasion we use line pumps, concrete hoppers and have on occasion used a tele-handler with a bucket on the end.

Does the concrete need vibrating?

On placement, it is advisable a vibrator is used to ensure that there are no voids are left in the concrete. R-WALL however has excellent fill efficiency, due to its lack of congestion within the walls and its unique "tie" system". This "tie" system has been designed to reduce resistance to the flow of concrete, thus ensuring a complete and uniform fill. 

How does the concrete dry between the layers of R-WALL boards? 

Concrete doesn't dry it cures. Hence why concrete can be laid below water. The curing process is a chemical reaction and one of the most important ingredients is water. Any loss of water can actually detriment the strength of the concrete (hence in summer when concrete dry's in the heat and cracks). The longer moisture can be maintained within the concrete the longer the cure and the stronger the concrete. R-WALL also aids the curing process by containing the heat from the reaction in the wall and preventing temperature fluctuations externally. 

How many storeys can be built?


Builds with ICF are limited to 18 meters maximum allowable height.

Does the bracing hold the walls up?

The formwork is self-supporting, the props do offer support but they are primarily used to adjust the straightness of the walls immediately after pour.  

How high can you pour concrete in one go?

We usually pour a full storey height at a time, up to approximately 3300mm.

How soon after pouring can the braces be removed?

As a general rule, we allow a minimum of 24 hours before removing the props.  Where we have cantilever overhangs which are propped, we leave it to the discretion of the structural engineer.

What stops the panels lifting during the concrete pour?

R-WALL rails clamp the boards within the channels and mechanically stop the boards lifting during the pour.  The R-Ties stop the outside panels from separating, giving a very robust formwork into which concrete can be poured.​ We also have a starter pack which is glued and screwed directly to the base or footing. 

Can I get a mortgage on an ICF house?

ICF was deemed a standard form of construction by the Council of mortgage lenders (a regulatory body for mortgage companies) provided the ICF system has a valid and UK accepted product certification such as the BBA. The council of mortgage lenders has now been merged into "UK Finance". UK Finance no longer specify specific construction methods to be deemed "standard construction" it is left to the lenders own risk appetites. The means that lenders can choose what they do and do not lend on, this goes for block construction, Timber frames or ICF, therefore it is advisable to approach your chosen lenders for acceptance whatever the chosen construction type.  R-Wall is BBA certified, provided the system is installed following this certification providers including but no limited to NHBC, LABC and Premier Guarantee all provide structural warranties.

How do you attach plaster board?

No need to "dot and dab". Plasterboard attaches straight onto the polystyrene, secured by screwing into the R-Rails. This offers significant time saving. Unlike other ICF's, R-WALL is designed for the UK market and works with our Metric building system. This has huge advantages. For example, many ICF systems will require cutting of plaster board in order to obtain a fixing, or studding off the walls to take the plaster board. This evidently results in more material, time costs, and results in increased width of the finished walls. Not R-WALL - simple, quick, narrower wall widths!

 Is the formwork weathertight?

The extruded polystyrene (XPS) is a closed cell matrix (no voids), unlike EPS (Expanded Polystyrene - small balls bound together). This closed cell system, makes the board impervious to water. This particular feature, utilising the higher grade polystyrene, is what sets us apart from the older/majority of ICF systems. 

 Can R-WALL incorporate a DPC or DPM?

Yes! Another R-WALL advantage! Unlike the majority of ICFs, it is easy to incorporate a standard DPC/DPM into the R-WALL formwork. Other ICF systems need to put a layer of waterproof concrete into the base of the build, that's not only very costly requiring specialist concrete, but also results in additional pump hire costs and time!

 What about floor attachment?

Intermediate floors are easily incorporated into R-WALL. A course of polystyrene is omitted internally and timber used instead. The timber is cast into the concrete using bolts and the joist hangers attached to the timber - a very simple and cost effective solution. There are also proprietary ICF joist hangers which are placed in the formwork prior to concrete placement and become cast in once the concrete has cured. For beam and block or concrete hollow core floors, the walls are poured and left to cure.  Once cured, the flooring is laid onto the concrete wall and then the formwork built up over and the floors cast in. Again, a very simple process. A further option is cast-in-situ concrete floors which can be designed to accommodate significant spans.

What about internal walls?

R-WALL is often used to construct internal walls, particularly when building apartments.  The system is flexible in that the polystyrene can be stripped back to expose the concrete core, or left on to increase thermal performance. The ability to build 212mm and 262mm concrete core walls is particularly useful for party walls. All proprietary internal wall systems from timber and metal stud to concrete block, are simple to tie into the concrete by exposing the core and using conventional mechanical fixings.

How thick are the walls?

Walls vary in thickness depending on the U-value required and the structural requirements designated by the engineer.  The thickness of the concrete core is easily altered with the choice of adjoining R-Tie system. We offer the choice of 6", 8", 10" and 12" to see the options please click here. The thickness of the insulation is altered according to desired Energy efficiency/U-Value. The options available are 50mm, 75mm, 100mm, 125mm and 150mm. Further details on insulation choices and resulting U-Values can be found by clicking here.

Can the system be used for basements?

Absolutely!R-WALL is arguably the perfect construction method for basements.  Modular block ICF systems are limited in terms of steel placement due to core congestion and fixed internal webbing. However R-WALL with its moveable ties and clear core is able to facilitate the use of steel mesh in construction - significantly speeding up build times. The lightweight nature of the system lends itself very much to building below ground and surprisingly substantial structures can be achieved quickly and simply with a relatively small workforce. The cost of basement construction with R-WALL is significantly less than almost all other build techniques.

What foundations are required?

R-WALL can be built off any foundation type and is in fact often used to create the foundations themselves. Strip footings can be cast using R-WALL formwork, as well as used to create a raft type foundation.

Why extruded polystyrene?

The simple answer is Extruded polystyrene (XPS) is a much higher quality insulation material compared to Expanded Polystyrene (EPS). XPS is a closed cell matrix whereas EPS is open cell. EPS is basically lots of small plastic balls heat welded together by compression. The very nature of "sticking" round balls together gives rise to voids and it is these voids that allow water to sit in the board or move through it. XPS however is plastic pushed through an extrusion mould and impregnated with air using a blowing agent. This forms a closed cell medium (no voids). Our particular board is blown using industry waste CO2 making it extremely environmentally friendly. In fact it has been awarded an A++ green energy award from BREAM.

This closed cell matrix also makes the board significantly more robust with high compressive strength, therefore less susceptibility to site damage, much stronger when pouring concrete and can be used under slab. 

The lack of voids also means XPS can achieve much better U-Value and much higher levels of airtightness and sound proofing, per thickness of insulation. Therefore R-WALL homes are much higher performing than other ICF systems using EPS. In fact we are proud to offer the highest performing ICF system on the market for wall widths to U-Value.

How is cladding attached to the walls?

One of the benefits of R-WALL is the fact that the plastic rails are cast into the concrete at 300mm centres. These rails provide a substantial mechanical fixing point for internal finishing sheet materials like plasterboard and cement board. Conventional external cladding systems like timber, slate, tiles, stone and brick slips are fixed back to the concrete core, as are more substantial finishes like brick, stone and granite quoins.

What about Render? How is that applied?

Straight onto the polystyrene! Renders such as Silicon or thin coat renders or those recommended by the manufacturer for use on ICF can be applied straight onto the polystyrene. Conventional sand, cement and lime render can be used but must be put onto a render carrier.

How are services chased into the walls?

Quickly and easily! Prior to plaster boarding, electrical services are easily chased into the wall by removing 20-25mm of material from the face of the internal polystyrene panel with the use of a hot wire cutter or multi-tool. Water pipes and 32mm and 40mm waste pipes are chased into the walls in the same manner if desired and even 110mm can be buried up to 80mm deep into the walls to keep boxing sizes to a minimum.

What is the lifespan of the resulting building?

Approximate expected lifespan of 100 years (subject to conditions)! R-WALL is built to last! Concrete only gets stronger over time, and R-WALL creates the perfect environment for curing. Because the board prevents water loss and maintains the heat of the reaction within the formwork optimum curing conditions are met creating stronger concrete. Also the board has a service life of the building and protects the concrete from the elements, thus further enhancing the concrete walls lifespan. The oldest concrete building today is 2000 years old! The oldest ICF home is nearly 60 years and still going strong!  This is the polar opposite to other systems. For example timber frame lifespan are often only stated to be 25 years! And that's only if it stays dry!! Not to mention all the movement and warping expected during timbers lifespan! 

Do i need to be a builder to construct using R-WALL

Evidently being a skilled and experienced builder is advantageous in any construction technique and that includes R-WALL. However with very minimal skills individuals are able to build successfully with our system. It is incredibly lightweight and straightforward to use. We insist individuals building with R-WALL complete a one day training with us. We offer unlimited telephone assistance, which accompanies the user manual and YouTube video support. For those users less experienced our trained experts can be employed on site to assist for longer periods as required by the customer. 

How much of R-WALL is recycled plastics? 

R-WALL is made from 93% recycled plastics! And the entire system being individual pieces is fully recyclable.

How can the R-WALL building be dealt with when it reaches the end of its usable lifespan?

The R-Rails and R-Board can be removed from the concrete separated and recycled. The concrete can be broken to to be used as hardcore or recycled aggregate and built with again. 

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