Welcome to the FAQ’s

This section lists some of the many questions Retrofit Academy staff and tutors have been asked over the years.

Why is 50m2 the smallest floor area noted for trickle vent numbers? The majority of the flats we install are under 30m2 with less than 5 windows.

The required number
(or equivalent area) of
background ventilators (trickle
vents) should be calculated in
accordance with the guidance
in Building Regulations
Approved Document F.

Is there a postcode search available for exposure zone?

Some SAP software does this. ‘BR 262 Thermal Insulation: Avoiding Risk’
includes a map, but it is small scale.

Do the requirements for fire doors override the PAS 2035 ventilation requirements for door undercuts? What guidance is there on the use of intumescent strips in this situation?

Yes, a requirement for a fire
door would override the door
undercuts requirement in PAS
2035 Annex C.
However, the ventilation could
be constructed with air inlet
and extraction in each fire
zone (e.g. SRHRRVs) in order
to meet both requirements.

Below DPC Insulation’ thermal resistance of the build up should be at least 0.75 of that acheieved through the main wall. Following this, the thickness of insulation below DPC would need to be MIN 100mm (as insulation types used below DPC cannot offer as good a thermal conductivity value of the phenolic insulation which is 0.22mm). This detail would result in a step out / ledge at DPC level. Is there a best practice detail for ‘Below DPC Insulation’ when the main system is phenolic (with a thickness between 60-80mm)?

There is currently no best practice detail available for EWI when the main elements
of the property are to be insulated with phenolic insulation.
Since the material placed below DPC is different, which is down to a requirement
for more robust water resistant materials to be used, the consequence is a reduced
thermal performance compared to phenolic. This then results in the step detail in

In the GHG, park homes are classed as high risk projects that must be delivered to PAS 2035. However, they are not referenced in the Construction and Built Form criteria in PAS 2035 Table B1. To which risk grade would they be assessed?

TrustMark has agreed that park homes are to be assessed as system-built, which
would result in risk grade B under criterion 5.
For park homes, insulation of the floor, walls and roof is treated as a single
measure (so all elements must be treated), and has inherent technical risk 3 in
Table B2, which results in risk grade B under criterion 3.

Are Retrofit Coordinators required to obtain full scale drawings under full SAP?

Full scale drawings are not a requirement of PAS 2035; however, they can be very useful to the Retrofit Designer and for project costing.

Are all solid wall properties considered “traditional”?

This is a difficult subject, and the full answer is under review.
The short answer is yes. However, it’s more appropriate to use an elemental
approach based on the actual characteristics of the various walls. The key point is
that just because a dwelling has solid walls, the construction might not necessarily
be vapour balanced, but could still be in moisture balance.
The key is not to unbalance it, but it may be possible to move the balance either
way (i.e. towards or away from ‘vapour open’).

What is a Significance Assessment and where can I find it?

The Significance Assessment is defined in BS 7913. There is a simplified version
(applicable in Path B only) on the BSI website, which can be downloaded for free.

What are all the software options for lodging work under PAS2030:2019 / PAS2030 (most frequent mentioned are Corelogic & Elmhurst, I hear there may be as many as 5 platforms)

TrustMark have said there are two methods of lodging into the data warehouse;
through the RC coordinator scheme platforms, the CoreLogic platform, or there is
direct lodgement into the data warehouse. These schemes must take responsibility
for compliance of their registered businesses and RCs.

The topic of verge trims has been discussed previously, but are you able to update us on any workaround solutions? Extending a roof will eliminate the affordability for many homeowners, is this therefore not an element of the design that can be included in the medium term plan

No, if you are installing EWI
then extending the eaves
and verges has to be done
at the same time as the EWI
is installed and may not be
deferred to a later stage of the
medium-term improvement
plan. There is a work-around product called
EWI Pro, and we understand from SWIGA
that they are also working on an alternative

My understanding is that I can be the Retrofit Coordinator for all pathways but for the design sign off my current qualifications and experience only allow me to sign off Path A & B conventional. To sign off Path B solid walls I would need either an external designer sign off or additional qualifications. CIOB offer a two-day course but having contacted them I have been informed that I would not be able to register with them based on that qualification. Is registration a critical element or is the Level 3 additional qualification sufficient to be able to provide sign off?

You only have to have the qualification; you do not need to be registered. Currently,
the RC can be the Designer in Path A and in part of Path B. The term sign-off is not in
the spirit of what we are doing, you should be overseeing the work and making sure
it is appropriate. The design is the Retrofit Designer’s responsibility, so you should
try not to acquire design liability.

Do you think we should be promoting Air Tightness testing and draught-proofing, as a rapid and cost-effective way of achieving energy reductions?

Yes, it is a perfectly valid
measure, but does not do
much unless you provide it
alongside other measures.

Can spray foam insulation be used under PAS 2030 and 2035?

Yes, because neither standard stipulates what type of insulation should be used,
the type of material is the project team’s decision (strictly the Retrofit Designer’s).
However, the project team is required to consider moisture risks and moisture risk

Do we need to move mains electric cables away from walls (i.e. distribution company) or do they fit something, shroud it and we go round it?

You do have to move them and
then put them back afterwards.
It is very dangerous to bury
cables under insulation as they
can overheat and cause a fire.

With regard to Q-Bot insulation, I understand that an analysis was carried out regarding the suitability of the product, was there a report that we would be able to see regarding this?

There is a report prepared by
Mark Elton which is available on
The Retrofit Academy Centre
of Excellence website. You can
acces this in your memebship
area here.

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E: info@retrofitacademy.org
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