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Wall insulation FAQ

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Do I need a planning permission for External Wall Insulation?

External wall insulation under the HES scheme may be exempt from planning permission. The key point is to keep the appearance of a house consistent with the character of neighbouring houses. In most of cases, the easiest solution to avoid any problems with planning authorities is to simply match the original appearance of the house.

SEAI advise however to contact local planning officer if there is any doubt about the future impact of external wall insulation on the character of local development.

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Who can do the work?

Accordingly with the HES scheme Terms and Conditions, insulations works must be completed by SEAI registered contractor chosen from the list of contractors. In order to register under the scheme all contractors must be insured to the minimum standards required by Sustainable Energy Authority of Ireland. Moreover, all external insulation contractors must be approved by National Standards Authority of Ireland (NSAI) prior registration under Home Energy Saving scheme.

Prime Insulation Systems Ltd is SEAI registered contractor under the HES scheme. If you wish us to carry out one of the insulation works covered by the Scheme grant please use our contractor ID: 14323 in the HES scheme application form.

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What is a cost of External Wall Insulation?

The actual cost of external wall insulation may vary, depending on number of factors e.g. amount of windows, required drainage and downpipes alterations, possible roof extensions, finishes, etc.

As every house is unique in some way, we always recommend to order our free quotation, which is based on short site survey. If you wish to order one please click here to visit our contact page.

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How long does it take to install external insulation?

It depends on the size of the house and area of its walls. In case of a typical terraced house (50 – 60 sqm of walls) insulation works should take about five working days, while a typical semi-detached (approx. 120sqm) usually takes 8 to 10 working days. Please note that those figures are based on assumption that there is no disruptions due to bad weather such as frost or heavy showers.

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How does it look?

The finish coat is available in almost 700 different colours and textures. To see some examples of finishes please visit our works gallery.

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How much is the grant?

To see levels of grant support available from SEAI please visit our HES insulation grant section.

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How to apply for insulation grant?

There are two methods to apply for a HES scheme grant:

  • Online – recommended as it takes only up to 3 days to get a response
  • By post – much slower up to 20 days response

Before applying for insulation grant please make sure that you have the following informations to hand:

  • MPRN number (electricity meter number) – you will find it on your electricity bill
  • Year of your house construction (must be before 2006)
  • Name and ID of insulation contractor (e.g. Prime insulation Systems Ltd, ID: 14323)
  • Your bank account details – grant payment will be transferred to this account
  • Email address (online applications only)

For online applications please visit SEAI HES scheme Homeowner section.

For postal application download the application form or request one by contacting SEAI on 1850 927 000.

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When will I be paid?

Grants are paid only after all works have been completed and you have fully paid all involved contractors and your BER assessor. It takes on average 4 to 6 weeks from the day when SEAI received correct paperwork to the day of payment.

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How thick is the external wall insulation?

Thickness of external insulation depends on the construction of the wall and has to be calculated individually for each house. In most of cases however a use of 100mm (4 inch) graphite enhanced EPS boards is sufficient to achieve required maximum U-value equal to 0.27 W/m²K. Allowing additional 15mm for the adhesive used to stick the insulation boards to the wall and approx. 5mm for base and finish coat, the total thickness reaches 120mm (almost 5 inches).

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How much will I save?

The actual savings will depend on the difference between current specification of the house (insulation level, heating system type and efficiency, percentage of low energy lights, etc.) and planned level of the upgrade. To make it simpler, let’s analyze two most common Dublin houses and anticipated savings after a few most cost effective upgrade works. Let’s assume that both houses have no external wall insulation, approx. 50mm fibre glass insulation in the attic, old pre-1998 gas boiler 68% efficient, 20mm thick lagging jacket on hot water cylinder, no heating control system and open fire room heater in living room.

The following simulations has been calculated on our request by SEAI registered BER assessor and are based on the most current ESB and Board Gáis energy prices.

Please note that heating bills costs have been estimated using standardised assumptions regarding household heating patterns and temperatures, heating season duration and mean external temperatures during the winter season in Ireland (i.e. 6°C for December, 5.3°C for January, 5.5°C for February).

TABLE 1: Annual savings on typical 3 bed semi-detached
Measure Original BER Original annual heating and electricity bills cost* Cost of the upgrade Grant obtained Net cost BER achieved Heating bills cost after upgrade Annual savings
- € € € € - € €
External wall insulation F 1,856 11,200 4,000 7,200 D2 1,342 514
Attic insulation D2 1,342 650 250 400 D2 1,254 88
New 110l hot water cylinder with 40mm factory insulation + cylinder thermostat D2 1,254 900 0 900 D1 1,175 79
Installation of condensing gas boiler and heating system controls upgrade D1 1,175 2,500 700 1,800 C1 890 285
100% low energy lights C1 890 50 0 50 C1 761 129
TOTAL COST 15,300 4,950 10,350 1,095
* Please note these prices are indicative only


TABLE 2: Annual savings on typical 2 bed terraced house
Measure Original BER Original annual heating and electricity bills cost* Cost of the upgrade Grant obtained Net cost BER achieved Heating bills cost after upgrade Annual savings
- € € € € - € €
External wall insulation E2 1,290 5,200 4,000 1,200 D2 1,037 253
Attic insulation D2 1,037 550 250 300 D1 963 74
New 110l hot water cylinder with 40mm factory insulation + cylinder thermostat D1 963 900 0 900 D1 889 74
Installation of condensing gas boiler and heating system controls upgrade D1 889 2,500 700 1,800 C1 686 203
100% low energy lights C1 686 40 0 40 C1 578 108
TOTAL COST 9,190 4,950 4,240 712
* Please note these prices are indicative only

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What is the U-value?

As per Building Regulations 2008 TGD Part L definition thermal transmittance or the U-value relates to a building component or structure, and is a measure of the rate at which heat passes through that component or structure when unit temperature difference is maintained between the ambient air temperatures on each side. It is expressed in units of Watts per square metre per degree of air temperature difference (W/m²K).

In simple words the U-value describes how well a building element transfers heat and the lower the U-value, the less heat is needlessly escaping.

In the design process or during retrofit works we should always aim to achieve as low U-value as possible. The Building Regulations 2008 TGD Part L sets out the maximum average elemental U-value as follows:

TABLE 3: Maximum average elemental U-value [W/m²K]
Fabric Elements New Buildings & Extensions to Existing Buildings Material Alterations to, or Material Changes of Use of, Existing Buildings
Pitched roof, insulation horizontal at ceiling level 0.16 0.35
Pitched roof, insulation on slope 0.20 0.35
Flat roof 0.22 0.35
Walls 0.27 0.60
Ground Floors 0.25 -
Other Exposed Floors 0.25 0.60
External personnel doors, windows and rooflights 2.20 2.20
Vehicle access and similar large doors 1.5 -

To calculate the U-value it is necessary to assess its reciprocal – the R-value.

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What is Thermal Mass?

Thermal mass is a building ability to absorb, store and then release the heat. Large thermal mass helps reduce the extremes in temperature experienced inside the home, making the average internal temperature more moderate and the home more comfortable to live in. For instance, when outside temperature is fluctuating throughout the day, a large thermal mass within the insulated house envelope can serve to "flatten out" the daily temperature changes, since the thermal mass will absorb thermal energy when the surroundings are higher in temperature than the mass, and give thermal energy back when the surroundings are cooler.

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