Welcome to the FAQ’s

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

Do we have to provide the tenant with the estimated capital costs of the measure as a registered social landlord?

Yes, you do, as required to do
so by PAS 2035.

Is there a standard software that is approved for Thermal Bridging calcs / Frsi calcs or can any software be used?

There are various options available but there’s not an approval process that we
are aware of. PAS 2035 states that calculations should be in accordance with BRE
Information Paper IP 1/06, which refers in turn to BS EN ISO 10211, so software
providers should be able to confirm whether or not this is the case. (There is
also another BRE publication: BR 497, Conventions for calculating linear thermal
transmittance and temperature factors by Tim Ward, Graeme Hannah and Chris
Sanders, which provides more detail on this and includes some worked examples.)

Could I get clarification that, come January, all path B and C jobs will require a designer with the qualifications of the current requirement for path C qualifications within Annex A?

What will be removed is the
option for the RC to be the
designer in path B but it would
be worth checking in the
revised document once it is
published to be 100% certain.

Regarding blocking up chimneys for a CWI measure, there is a concern that where there is residue of soot left in the chimney and a lack of ventilation if the balloons are used, this can potentially cause sulphur and condensation to react and eat away at the brick. Thus, what would you advise with blocking chimneys up, reducing this risk, and installing background ventilation?

We have traditionally
blocked up chimneys and
left them ventilated to avoid
condensation and would
believe this to still be good
practice. Chimney balloons
could be an option, but we
wouldn’t have thought that
these can seal the chimney
particularly well.

Regarding the insulation of park homes, we understand the IAA’s Retrofit Coordination service is signing off single measures such as EWI and UFI to this property type (putting other insulation measure in the medium-term plan). Is this an approach that the wider industry is now likely to adopt, as for several months we had been under the impression that park homes must receive wall, loft and underfloor insulation at the same time?

It is true that in PAS 2035, insulating a park home is one measure and therefore
you would be expected to insulate the walls, the roofs and the floors. There is a
guide being written (and commissioned by BEIS) so it is waiting for, and referring
to, that.

As a coordinator, I have clients who install under ECO, lately with it being close to end of the month, the installers have been physically instructed by their funder (energy company) to backdate installs so they can hit their LTS targets. What are your thoughts on this as this is apparently an industry-wide common occurrence, this would mean on lodgement although the correct process has been followed (I.e., contacting and confirming with the client prior to install), but now they are wanting to physically change the install dates as instructed by the energy companies?

Part of TrustMark’s audit process is to look at all the documents on lodgement to
make sure they have all the corresponding dates and also there’s an implication
of the financial protection dates because they all have to line up. If there are any
mismatches, TrustMark can accommodate and make changes as long as all the
documentation is provided to support this request.

If I have an EWI property, can I fit verge trims to the top of the system and put the changing of the trim in the medium-term plan when the roof is reroofed in say, 5 years’ time? I’m of the opinion that as it’s part of the measure being installed then this wouldn’t be allowed as it’s not a measure on its own but part of the system being installed (and PAS 2030 – 2019 states not to use verge trims) but I’m getting different responses from other Coordinators, Designers and Installers?

Correct, PAS 2030 and PAS
2035 both ban trims. No types
of trims are allowed because
there is too much evidence
that (especially) when not
properly installed, they let
water in behind the insulation
and can do some substantial

Are RC’s site visits mandatory in the new version of PAS? How will TM police this? and with a shortage of RC’s how do you think this will affect the ECO sector?

Both PAS 2030 and PAS 2035 say that the work on site is done on the oversight
of the RC and we feel that any RC who doesn’t visit site is taking a huge
professional risk. The Retrofit Academy always teach through our qualifications
that RC should be present on site and ensure things are done in a compliant

Please could you define what you mean by “adjacent to hob” when calculating extract rates for ventilation?

There is no mention of “adjacent
to hob” in PAS 2035, it is entirely
a Building Regulations approved
document F concept, so that is
where you need to look for the
definition. Our understanding
is that it effectively means
a cooker hood that extracts to outside the

My understanding of PAS 2035 is that the presence of an openable window in a space justifies a ‘tick’ for Purge Ventilation for that space. Surveying an existing home for the Ventilation Strategy, I found a room which had a purge area 1/100th of the room’s floor area – i.e. 1/5th that required to meet Building Regs Part F. Since the room had a window which was openable, the room ‘passed’ for PAS2035 Purge Ventilation, but I felt uncomfortable with this designation. What are your thoughts on this?

We feel you are right. If you look at Part F about Purge Ventilation it does require
the openable window to have a certain proportion of the ratio of its area to the floor
area of the room (generally 1/20th but it depends on a number of factors including
the type of window). We feel that there could be a mistake in note 5 of C.2.3 in PAS
2035 and that more clarity may be needed.

Am I right in thinking there are still only 250’ish Retrofit Coordinators trained and working? If so, how are they going to cover all open retrofit programs?

There are currently around 1000 trained and qualified Retrofit Coordinators and we
plan to train many more over the next twelve months through a number of channels:
online bootcamps, classroom training and the roll out of new Retrofit Academy
regional training centres across the UK. Much of this programme is supported by
funding from BEIS and/or local bodies. What we are unsure of, at this time, is exactly
how many Retrofit Coordinators will be needed to deliver the 2050 targets, over the
next twenty-eight years.

How can the onsite visits work in a commercial environment, such as ECO? These ideas work for deep retrofit projects, but won’t these measures reduce the volume?

PAS 2035 requires the
adoption of a whole-dwelling
process that manages and
reduces technical risks in
order to protect the house
and the householder, and
which includes the Retrofit
Coordinator having an appropriate level of
oversight of installation work on site. It is
understood that under-funded programmes
such as ECO will not be able to deliver as much
work that is PAS 2035 compliant as they did
prior to PAS 2035 being introduced. Since we
know that for retrofit projects that go wrong
the time and cost associated with remedial
work are many times more than the time and
cost associated with doing the work properly
in the first place, it would be unwise to inhibit
the Retrofit Coordinator’s oversight of work.

In the IWI Best Practice guide published by BEIS, it states that for internal solid wall insulation installed with a ventilated cavity behind, there is a requirement to install ventilation to the exterior at the top and bottom for every stud. We have received confirmation from a manufacturer that as long as we follow their guidance, this is not required. Is this acceptable?

It has always been good practice to include a ventilated cavity on the cold side
of vapour closed IWI insulation, in order to remove moisture that migrates from
the interior, through the ventilation layer, and becomes an interstitial condensation
risk. Without the ventilation including the cavity is pointless. This is confirmed
by the BEIS Guide to Best Practice for Retrofit Internal Wall Insulation, clause 45.
Also, PAS 2035 clause 9.1.11 requires the design to have a coherent approach to
managing moisture risk consistent with BS 5250. In many cases, this will require
hygrothermal condensation risk analysis in accordance with BS 15026, and the BBA certificates for
some IWI products specify this. Therefore, the Retrofit Designer should carry out the appropriate
condensation analyses, confirm that the design has taken this into account, and take responsibility
for the decision whether to include a ventilated cavity or not. Some suppliers of IWI products have
provided conditional guidance on when a ventilated cavity might be omitted, but responsibility for
the design still rests with the Retrofit Designer.

Where do we stand with Retrofit Designers and Traditional Buildings? We are struggling to find people with the right level of qualifications.

This is a classic supply chain
failure. There are not enough
Retrofit Designers qualified
to work on traditionally
constructed and protected
buildings. The Retrofit
Academy is encouraging
the professional institutions’ conservation
schemes to run more courses and to let us
know who the qualified professionals are. We
have also acquired a licence to deliver the
Level 3 training required for Retrofit Assessors
working on traditionally constructed buildings,
and we will be offering that training in due

Is it mandatory that the Retrofit Coordinator needs to carry out site visits?

PAS 2035 specifies that
retrofit installation work on
site must comply with PAS
2030 and be overseen by the
RC. The installer is required to
give the RC access to work on
site for inspection. The RC is
therefore expected to visit site at appropriate
intervals during the course of the work, and
preventing him/her from doing so would be
non-compliant with both PAS 2035 and PAS

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