External Wall Insulation Cost Guide

External Wall Insulation Cost

Why should I even consider installing External Wall Insulation system to my house? It seems to be one of the most expensive ways when trying to save on my heating bills, the disruption to me and my family will be unbearable and I will need to re-paint the façade every year as well.

These are the common misconceptions regarding purchase, installation and after care of External Wall Insulation systems. At EWISTORE we offer the best products that will eliminate these worries and clarify such misconceptions.

External wall insulation cost – there are three main factors that need to be considered when you think of installing solid wall insulation:

1.       Cost of materials

2.       Cost of installation

3.       Investment efficiency

Cost of materials – all the materials we offer are shipped to us directly from manufacturers. We don’t use any middlemen that would hike the price of each product and therefore increase total price of external wall insulation systems. That way we can and do keep the cost of each item to one of the lowest in UK without at the same time compromising on quality. Easiest way to calculate the cost of exterior wall insulation is to calculate square acreage/meterage of your property and multiplying it by:

·         45.00GBP+VAT – acrylic

·         50.00GBP+VAT – mineral

·         65.00GBP+VAT – silicone

·         110.00GBP+VAT – EXTREME

Prices given above may vary in certain circumstances and more detailed information is required before a quotation can be prepared. However these figures will allow you to roughly calculate the cost of external wall insulation materials for your project.

Cost of installation – no matter how good the materials you’ll buy are, you will need a team of professionals to carry out the installation. Otherwise the external wall insulation system will not be able to perform as desired. Cost will vary substantially depending on your location and the amount of work required. As a distributor we cannot give definitive figures but from experience we know, that prices vary from 35.00GBP – 100.00GBP and above per square meter.

Investment efficiency – various energy providing companies estimate that solid wall insulation will give between 495.00 – 790.0GBP+VAT per annum. Specific figures will vary according to your property’s wall construction, exterior wall insulation system used and energy tariffs. When combined with loft insulation, house is tightly wrapped up and you will be able to notice boiler coming on less and less.

There are other aspects of exterior wall insulation systems that are often forgotten by house owners and developers:

·         First aspect is environmental, as EWI system will cut carbon dioxide footprint of the property.

·         Second is the health aspect, simply because properly installed outside wall insulation will prevent mould and damp (providing such problems did not exist prior to EWI system installation).  

·         Thirdly, your property will benefit from a fresh look, with huge choice of colours (mixed to your choice on site at EWISTORE warehouse), texture and impact resistance.

·         Lastly, as external wall insulation supplier, we pride ourselves in offering self-cleaning finishing coats, highly durable, weather resistant and long lasting.

EXTERNAL WALL INSULATION - COMMON MISTAKES

EXTERNAL WALL INSULATION - COMMON MISTAKES

·         First of all and very obvious – use best quality products! Check that the materials you buy are certified! Look out for CE marking on packaging and ask for copy of ETAG 004 certificate that relates to EWI systems. At WWW.EWISTORE.CO.UK we only offer products and systems that comply with all the above requirements.

·         Surface preparation – probably most commonly occurring mistake is the lack of or poor preparation of the surface onto which the EWI system will be applied. Due care must be given to cleaning walls of dirt, dust, paint, old render etc. See our STEP by STEP article for guidline on this stage. You will recognise a good installer by the fact that he will carry out the test on the wall. This will show whether the surface is suitable to accept EWI system (see point 4: Substrate suitability check)

·         EPS boards installation mistakes – do not align sheets! Use stretcher bond when installing polystyrene sheets. Othwerise they will not be able to perform as designed by manufacturer. In areas like corners of building, secure polystyrene with additional mechanical fixings. Any gaps over 2mm between boards should be filled with polystyrene. Never use adhesive (foam or mixed compound) to fill the gaps!!! This will lead to the effect of cold-bridging and heat-loss.

·         Even surface – buy a polystyrene rasp and a long spirit level. When boards are installed make sure they make a flat area. The surface of EPS must be free of any irregularieties. Since finishing render and reinforcement mesh with adhesive make a thin layer, all uneven spots will show later on and can lead to heat loss.  

·         Even surface – buy a polystyrene rasp and a long spirit level. When boards are installed make sure they make a flat area. The surface of EPS must be free of any irregularieties. Since finishing render and reinforcement mesh with adhesive make a thin layer, all uneven spots will show later on and can lead to heat loss.  

·         Fibreglass mesh – make sure the one you buy is the right one. We offer different size and strength rolls of mesh from BUDGET one (145g/m2 and 50sqm) through PREMIUM (158g/m2 and 174 g/m2 – both 55sqm) to EXTREME (335g/m2 – 25sqm). Choose the one that is most suitable for your project.

·         Mesh layer – when applying fibreglass mesh on MESH adhesive make sure to overlap at each layer. Usually around 15cm overlap is enough. When calculating for materials required, allow for the actual usage of each mesh roll. 50sqm of roll will cover around 45-46sqm of façade due to overlap.

·         Windows/doors openings – when adding mesh in openings corners, use diagonal strips of fibreglass mesh to prevent cracking and enhance strength of reinforcement layer. At WWW.EWISTORE.CO.UK we offer revolutionary product – LINTEL MESH CORNER BEAD 5941 – this will allow to speed up process of mesh application and provide superb quality and strength around openings

·         Biggest mistake ever – fibreglass mesh applied directly onto EPS board and mesh adhesive added on top of mesh! This is the worst possible scenario ever!!! Mesh adhesive must be applied evenly onto EPS board, then mesh itself “inserted” into the layer of adhesive and again spreading the adhesive again to achieve consistent and even layer of reinforcement.

·         Weather conditions – rain, temperature, even intensity of sunlight – all these factors must be taken into account before even starting EWI project. It is not recommended to work when temperatures fall (or might soon fall) below 5°C.  Rain and acrylic render are not best friends! Protect your façade when applying render if you think it might be raining soon. And don’t forget to protect the property you are working on when the sunshine is particullary intense.

These are most common mistakes when installing External Wall Insulation systems on your property. What might seem at first as very complicated process, installation of Solid Wall Insulation is in fact quite straightforward for an experienced installer. If in doubt – ask. Don’t hesitate to contact us at: info@ewistore.co.uk if you are unsure about the work carried out on your house. And if you are looking for a good team to do the job, we will help you to find it!

STEP BY STEP EXTERNAL INSULATION INSTALLATION

STEP BY STEP EXTERNAL INSULATION  INSTALLATION

1 Surface preparation:
As with every other job, preparation is extremely important. Before applying EPS insulation, you will need to examine and check wall surface. These should be clean, dry, dust-free, cleaned of paint and other substances that might affect the way EPS adhesive will perform. One of the best ways to achieve clean and ready surface is to use high pressure water-jet or prepare wall mechanically (wire brush).



2 Determining surface condition:

As the external wall of the property will hold the whole weight of external insulation system, it is crucial that special care is taken while determining its condition and suitability. It is recommended that existing render is hacked off from window and door surrounds, so that new 2-3cm thick insulation can be added at a later stage. Any cracks, un-even surfaces, dents up to 10mm should be made good and even using leveling mortar (LEVELLING MORTAR W). Any wall areas that are more than 20mm off level should be made good using EPS insulation of appropriate thickness.


3 Surface priming:
First priming should be applied prior to installation of EPS insulation. Absorptive and dust-generating substrates should be primed with PRIMER-N. It is required that all surfaces are primed after they have been mechanically cleaned (high pressure water jetting and wire brushing)


4 Substrate suitability check:
One of the most forgotten aspects of preparation prior to EPS insulation installation and therefore common mistake is the lack of proper inspection of surface. With little cost in terms of money and time, this simple yet effective way will allow you to determine and make sure that the substrate is suitable to accept External Wall Insulation. After priming, prepare a few EPS insulation samples, approximately 8-10 of them around 10 x 10 cm. Apply those using EPS adhesive in various places on the wall. These samples should be left on the wall for around 3 days. Then try to take them off the wall by simply pulling them off the wall. The result we are after is the disintegration of the polystyrene, with part of each sample still on the wall safe and secure and part of it ripped apart. This will determine the substrate suitability for external wall insulation application. If however the polystyrene will come off easily with adhesive off the wall, this will show you that surface has not been prepared adequately or lacks the strength to hold outside insulation. In such situation priming and preparation should be carried once more and mechanical fixing of EPS insulation re-designed for allowing of lack of adhesion.

5 Starter track installation:
Prior to polystyrene application you will have to install starter tracks. At WWW.EWISTORE.CO.UK we offer 2 types of this product. Standard aluminium start track (ref: STARTBEAD) or PREMIUM, cold-bridge free PVC with fiberglass mesh (ref: PREMIUMSTART4210-4216).
Firstly, use chalk line or laser to determine straight line around the property on the level on which the track will be installed. Starter tracks are then fixed using rawlplugs, no less than 3 each meter. Aluminiumtracks should be connected using PVC starter track connector.
Starter tracks will allow to achieve a straight and neat bottom line of the whole external insulation system applied to property, protect from weather, damp and other damages.

6 Adhesive preparation:

The right preparation of EPSadhesive is absolutely crucial. EPSadhesive Z should be mixed with clean water 4.8-5.3 litres/25kg bag. The compound should be mixed using heavy duty power plaster mixer on slow-rotating setting. Freshly mixed compound should be left for approximately 10-15 minutes and then re-mixed for a short period of time. Bucket life is approximately 1 hour. Every 15-20 minutes compound should be mixed/stirred a few times during application.




7 Applying ESP adhesive onto polystyrene insulation:

The best and recommended way to apply ESP adhesive onto EPS insulation is through modified “Dot and Dab” method. With trowel you need to apply adhesive evenly around the edges of polystyrene (3-4cm wide track) and inside that area Dot and Dab “spots” (approximately 4-7 of them). After sticking polystyrene sheet to the wall, adhesive should not protrude from under it. In general, EPS adhesive should cover no less than 40% of the surface of insulation sheet.

8 External wall insulation polystyrene around windows and doors:
 

When installing EPS sheets around window and/or door openings it is important that the joints between boards are not in line with window/door openings. This will prevent cracks appearing in the future. For best result and ease of installation we recommend use of Lintel Mesh Corner Bead (ref: LINTELCORNERBEAD5941)

9 Level control:

Do not forget the obvious – to control both horizontal and vertical alignment of the EPS boards during installation. For best result use STRAIGHT EDGE WITH SPIRIT LEVELS (see:WWW.EWISTORE.CO.UK: MISCELLANOUS → TOOLS)

10 Filling gaps between EPS insulation boards:

Where the gaps are larger than 2mm, you will need to fill them with polystyrene strips. Common mistake is to use EPS adhesive for gap filling. This can lead to a formation of cold-bridge and cracks where joints are.

 11 Polystyrene boards surface leveling:

EPS insulation boards surface must be smooth and level throughout the facade  All un-even areas should be made good prior to applying reinforcement layer. For this job please use polystyrene rasp . Smoothing of EPS boards should take place no earlier than 3 days after installation.

12 Mechanical fixing:

At EWISTORE.CO.UK we offer standard (POLYST-FIX) and premium (POLY-FIX) mechanical fixings  for polystyrene. Both types will provide additional secure fixing of external wall insulation to the solid wall. Standard fixings are plastic (plug and rod). Premium have plastic body and metal rod with plastic head for cold-bridge prevention. Holes drilling for fixings should take place no earlier than 3 days after EPS boards installation and prior to adding reinforcement fibreglass mesh . It is commonly recommended that between 4-6 fixings are used per square meter of insulation. More on edges of properties, where wind factor is higher. After both plug and rod are inserted (approximately 20mm into polystyrene), top of the holes should be filled with a round cap to prevent cold-bridge effect. Be careful not to insert the fixings too deep into polystyrene as this might cause the insulation board to crack and lessen the strength of the EWI system. Round caps should not be „glued” using EPS adhesive

13 Preparation and application of MESH ADHESIVE for reinforcement layer:

For reinforcement layer please use MESH/EPS UNIVERSAL ADHESIVE U. The contents of package should be mixed with water (4.5-5.0L/25kg). Bucket life is approximately 1.5h. The compound should be mixed using heavy duty power plaster mixer on slow-rotating setting. Freshly mixed compound should be left for approximately 10-15 minutes and then re-mixed for a short period of time. Every 15-20 minutes compound should be mixed/stirred a few times during application. Water should not be added to the already mixed compound at a later stage. Once ready, MESH adhesive is applied (using combed trowel) onto polystyrene boards in an even layer of about 3mm. After this stage, fiberglass mesh is applied onto the freshly laid MESH adhesive. Reinforcing mesh should be flat and evenly spread. Mesh should be covered within adhesive but applied without excessive force as not to driving it directly onto surface of EPS board underneath. Another layer of MESH adhesive should then be applied to cover the already installed one and mesh. It is crucial that both layers of adhesive and mesh are added at such intervals of time, that neither dries in-between and all together make one consistent layer. Fibreglass mesh should overlap another section by approximately 15cm. double layer and use of high strength (MESH HD 335) mesh is recommended on lower parts of property, if there is a high risk of mechanical damage occurring (high street, schools, public buildings). Please ask EWISTORE team for more details. Reinforcement layer installation must be carried out to a level and even finish, otherwise any imperfections might show on the finishing layer of render.

14 Render primer:
After reinforcement layer is dry and not earlier than 3 days after its installation, we can start priming the surface to make it ready for final render. Depending on the type of render, there will be a different type of primer (PRIMER OP or PRIMER SIG). Application of primer is easy and straightforward. Simply use roller or brush to spread the primer evenly on the surface of reinforcement layer. Application temperature should be between 5-25°C. Primers should not be diluted.

15 Finishing render preparation and application:

After PRIMER has dried, but no earlier than 24 hours after application, you can start adding final layer of render. At EWISTORE we offer ready mixed ACRYLIC, MINERAL render in bags, SILICONE render and SILICONE paint. ACRYLIC and SILICONE renders are ready to use. Simply stir them thoroughly before applying and that’s that! It is of utmost importance to stick to manufacturer’s advice on weather conditions. Please check the packaging or email us at INFO@EWISTORE.CO.UK for data sheet of the product.

ACRYLIC and MINERAL renders application is very similar. Using steel trowel apply it from bucket onto wall and smooth it out. Take out the excess of product. Then with PVC float or POLYSTYRENE float and by round/circular movements of hand, spread and „texture” render. Altough at first complicated, the application procedure is in fact easy and straightforward. We recommend to practice on a smaller area at first. Remember to have enough tradesman on site and scaffolding in place. Otherwise you might have the end effect, where lines between separate layers are visible. TBC.......

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