Question 1

What type of foundation is best for SIPs?

Accepted Answer

Many different constructions can be used but the tolerance to level must be +/- 5mm to ensure the most efficient erection of the SIPs panels. The most common practice is to build up a dwarf wall in block from the poured foundations which the SIPs are fixed to. Foundations for SIPs tend to be a strip foundation with a ground bearing slab.

Question 2

Wall heights - how high can I go?

Accepted Answer

Our standard panels are 2.4m x 1.2m. However, higher walls can be built by adding a short panel on top of a tall one, and so on.

Question 3

Whats the best heating system for a SIPs house?

Accepted Answer

Any conventional heating system can be used although SIPs are ideally suited to innovative and energy-efficient solutions. Your ventilation strategy will have a big impact on your heating decision, but we would generally advise installing a mechanical ventilation with heat recovery (MVHR) system to cut heat loss.

Question 4

Is an MVHR system necessary for SIPs buildings?

Accepted Answer

Yes, an MVHR system is recommended for SIPs buildings to ensure a fresh air supply, control condensation, remove pollutants, and maintain efficient appliance operation. Discuss this with your building's main designer.

Question 5

What can SIPs be used for?

Accepted Answer

SIPs can be used in place of any traditional build method for walls or roofs allowing the building to be completed in less time and with a greater level of thermal insulation.

Question 6

How do SIPs react to fire?

Accepted Answer

The OSB (Oriented Strand Board) skins and the foam core materials do have some degree of resistance to the spread of fire but to ensure that construction fully complies with building regulations, internal walls are usually lined with a 12mm fire-resistant plasterboard which can then achieve a 60-minute fire rating.

Question 7

Can the services be installed within the SIP's walls?

Accepted Answer

No. The SIP panel is a thermally-efficient airtight product that works best without services running through. We recommend the use of a counter batten to create a service void for electrical wiring and fixtures to be installed. If required on external walls, they can be surface mounted and then boarded over.

Question 8

What U-values do the SIPs achieve?

Accepted Answer

Our standard wall panels can achieve U-values from 0.14 without additional insulation. Visit our technical section here for more details on specific panels.

Question 9

What type of foam insulation do you use?

Accepted Answer

Our standard panels have a core of modified Expanded Polystyrene (EPS). EPS foam provides lower U-values than other types of foam and does not contain chlorofluorocarbons (CFCs), which could deplete the Earth's ozone layer. The U-value of our panels is extremely stable so values remain constant in both hot and cold temperatures.

Question 10

Can I get a re-cycled plastic or a more sustainable insulation material?

Accepted Answer

Our ambition is to develop our own environmentally-friendly insulation. We're currently busy connecting with the sector's most innovative suppliers, on a search for one that shares our vision for more sustainable building methods and materials. To learn more about this ambitious project, please check our news page.

Question 11

Do I need MVHR (mechanical ventilation with heat recovery) ?

Accepted Answer

An Ecologic SIP build system provides a vast improvement on air tightness as compared with more traditional construction methods, therefore careful attention needs to be considered to the ventilation method to create and maintain a healthy living environment.

Question 12

Can I use SIPs for the ground floor?

Accepted Answer

This is certainly common in smaller garden room type buildings in SIPs and technically possible in a full scale house build also. SIP floors should always have a minimum of 50mm airflow gap below. The ground beneath SIP floor buildings should be graded with a permeable membrane and/or Type 1 MOT/gravel cover or alike.

Question 13

What about shrinkage in a SIPs structure

Accepted Answer

Whilst we can't say there will be no movement in the structure it will be to an absolute minimum. The fact that the panels are one laminated entity with two sheets of structural sheathing to both the inner and outer face means shrinkage is reduced when compared to an equivalent typical timber frame construction.

Question 14

Where should I position windows and doors within the thickness of SIPs walls

Accepted Answer

You get best thermal performance by centering the window within the SIP insulation. The two key things are: To make sure the thermal resistance through the insulation around the frame is high enough to avoid a cold bridge (you will achieve this as long as the front face of the frame is no further forward than the front face of the insulation within the SIP or if it is then an...

Question 15

Can I have brickwork on the outside?

Accepted Answer

Yes, the brickwork would form the outer leaf with a minimum 50mm cavity separating it from the internal SIP wall leaf.

Question 16

Can you have a chimney in a SIPs building?

Accepted Answer

Yes, traditional style working chimneys can be integrated into a SIPs build. There are specific details and systems available for this purpose and we can work with your architect to ensure their design for this works with our SIPs install. Specifically, Isokern have a range of highly heat-insulating pumice stone systems which are suitable for this purpose.

Question 17

How to improve the thermal junction at the sole plate (Blockwork Alternatives)

Accepted Answer

The blockwork we normally recommend is a Thermalite 7N block https://www.forterra.co.uk/product/thermalite-aircrete-hi-strength-7/ which has a better u-value than a standard dense concrete block.

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