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The inside face of a tall metal-clad wall in an empty UK industrial unit, vertical profiled sheet between cladding rails, pale daylight from a high window along the wall.

Application

Walls, sealed from inside: metal cladding, timber stud or masonry, one continuous layer with no air gaps.

On a metal-clad wall the foam follows the profile and closes the rails and fixings. In a stud wall it fills the whole cavity. Against masonry it bonds directly. In every case the convection loops that defeat batts and boards are gone.

Start a project brief What it costs: the cost guide
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Is this your wall?

01The build-up

The cladding stays. The layer follows it from inside.

A single-skin metal wall is the same problem as a metal roof, turned on its side: thin cold steel, a profile a board cannot follow, and rails and fixings that let warm, wet air through. Water forms on the inside face and runs to the floor. Switch the drawing between the bare wall and the sprayed wall.

Two states. Switch between them; the marks and the reading follow.

Swipe across to see the whole section.

BARE CLADDING · COLD STEEL, WET FACESection, schematic, not to scale. Three marks in each state; the cards beneath read them.

Cold steel · below the dew pointThe dew point · water formsAbove the dew point · dry

1The cladding sheet

Thin, cold, and wet on the inside.

Profiled steel a millimetre thick between the weather and the building. In winter its inside face sits below the dew point of the air in the room, and that air gives up its water onto it.

2Rails and fixings

Every rail and every fixing is a path.

Warm, wet air reaches the cold steel at every lap and fixing, and the rails carry cold straight through. A board or batt fitted between the rails leaves the profile and the joints open behind it.

3Water on the inner face

It runs down and pools at the floor.

Condensation on a wall does not drip; it runs. Stock, plant and the slab edge stay wet, and the steel corrodes from the inside.

The short version: on a wall, convection is the enemy: any air gap behind an insulation becomes a loop that carries heat and moisture to the cold face. A sprayed layer has no gap. That is the whole argument, for cladding, stud and masonry alike.

02Project record

The sequence, on a real wall.

Installation footage from HOLVEM's own projects. This item is a project record, played on request; nothing on this page that is not real footage carries that label.

Project recordWalls sprayed and sealed
Walls sprayed and sealed in continuous passes. Closed cell, from inside, the profile followed.

Continuous passes, the profile followed.

The applicator works along the elevation, each pass overlapping the last, the layer taking the shape of the cladding as it cures. What you see is the face the building will have from then on.

All project records

03The order of work

Five steps, from inside.

The work is done from inside the building, elevation by elevation, with the cladding untouched. Stud and masonry walls follow the same order with their own preparation. Each step is checked before the next begins.

  1. Substrate condition

    Cladding, rails, fixings and the base detail are inspected: corrosion, damaged sheets, water ingress at the base. For a stud wall, the studs and sheathing; for masonry, the state of the face. Ingress is repaired first, by someone else.

    HOLVEM checksSound, dry and weathertight before any foam goes on.

  2. Preparation and protection

    Corrosion product, loose coating, dust and oil come off the inner face. Stud cavities are cleared of debris. Masonry is brushed down. Services on the wall are protected or re-routed, and the floor sheeted.

    HOLVEM checksClean, dry, keyed surface; everything in front of the wall protected.

  3. Passes and depth

    Foam is sprayed onto the inner face in passes, following the profile or filling the cavity, to the specified depth. Closed-cell for cladding and masonry; closed-cell or open-cell in a stud wall depending on the objective.

    HOLVEM checksApplied thickness measured and recorded, elevation by elevation.

  4. Coating or lining, where specified

    Where the foam stays exposed and a reaction-to-fire classification is required, an intumescent coating is applied over closed-cell foam. Where the wall is lined, the lining usually carries the requirement.

    HOLVEM checksCoverage logged where a coating is specified.

  5. Terminations

    The base detail, window and door openings, columns, roof junction and penetrations are detailed per project. The layer stops at a closed, coated edge, and services that need access are stopped short of, not sprayed over.

    HOLVEM checksEvery stop closed and detailed.

A close detail of the inside of a bare profiled metal wall between two cladding rails, fixing heads and a run of dark staining down the sheet.
BeforeThe bare cladding, from inside
The substrate as it is inspected: the profile, the rails, the fixings, and the water marks that say what happens in winter.

Every step is checked before the next. Thickness measured, coverage logged, compiled into a QA record at completion.

04Preparation

Before the first pass: what the wall has to be.

Walls differ more than roofs do. Three things HOLVEM establishes on every wall, whatever it is built from.

Which wall it is

Cladding, stud or masonry sets the system.

Closed-cell bonds to steel, masonry, stone and brick as well as timber. Open-cell is for timber and board substrates only, where sound or breathability is the objective. The substrate decides which is even possible.

Clean and dry

Adhesion is decided here.

Corrosion product, loose paint, dust and oil come off; damp masonry is dried or the design changes. A failed bond fails the seal.

The base detail

Where the wall meets the floor.

The slab edge and the cladding base are where water collects and where the layer has to stop cleanly. It is drawn per project before the work starts, and checked on the day.

Survey, or photographs?How HOLVEM works: we understand your project before we price it

05Thickness and objective

The depth is set by what the wall has to do.

Three objectives, three depths, each a direction for the survey to confirm on your wall with the rails or studs in the calculation. What it costs is on the cost guide, not here.

25 mmCondensation control

Keep the inside face above the dew point.

Enough to stop the wall running on most single-skin cladding: the face the air touches is the foam, and the laps and fixings are closed. The objective where the building is unheated or lightly used.

50 mmHeat retention

Hold useful heat in the building.

Controls condensation and keeps warmth in, so the heating works less hard.

75 mm and aboveA calculated U-value, or sound

A figure to meet, or a quieter wall.

Set by the U-value the project has to reach, calculated with the rails or studs included. In a stud wall, open-cell at full cavity depth is specified where airborne sound between spaces is the objective.

The inside of a metal-clad wall with a continuous cream closed-cell layer following the profile between the rails, the rails enclosed, even daylight along the wall.
AfterThe layer, following the profile
The finished face: continuous, following the cladding profile, the rails inside it, ready to be left, coated or lined.

Thickness and objectiveWhat it costs: the cost guide

06Where it suits

The buildings whose walls need it.

Single-skin metal walls are everywhere in UK industry and agriculture; stud and masonry walls are everywhere else. Three building pages where this application is common.

Building

Industrial units and factories

Metal-clad walls that run with condensation in winter and radiate heat out all year, sealed from inside without stopping production.

Read the building page

Building

Workshops and garages

Clad or blockwork walls in small buildings that are cold to work in and damp by morning.

Read the building page

Building

Modular and portable buildings

Thin-walled cabins and modular units where a sprayed layer adds insulation without taking the floor space a lining would.

Read the building page

Every building type HOLVEM works on

07What HOLVEM checks

Three things checked before anyone talks about depth.

HOLVEM does not quote a depth from a photograph. The wall is understood first: how it behaves in winter, whether fire performance is required, and what U-value it must reach.

Condensation risk analysis

Will the inside face stay above the dew point?

A condensation risk analysis to BS EN ISO 13788 for the wall as built, with the internal conditions the building actually runs at. Where the simple method is inconclusive, HOLVEM runs a dynamic simulation to BS EN 15026.

Fire

Is a reaction-to-fire classification required?

Where it is, and the foam stays exposed, the coated closed-cell system is specified, classified B-s2,d0 in the build-up tested. Where the wall is lined, the lining usually carries it. Established before the depth.

U-value

What figure does the wall have to reach?

Calculated to BS EN ISO 6946 for this build-up, rails or studs included, not read off the foam's own conductivity. The calculation is yours to keep.

Condensation risk analysisU-values and Approved Document LFire performance and coatings

08Straight answers

Ask us the hard ones.

The questions people with a cold or wet wall actually ask on the call, answered the way the specialist answers them.

Can you spray a stud wall as well as a metal one?
Yes. In a timber or steel stud wall the foam fills the whole cavity, so there are no convection loops or air gaps behind the lining. Closed-cell for the most insulation in the least depth; open-cell where sound between spaces or breathability is the objective.
Does the foam stick to brick and block?
Closed-cell foam bonds directly to masonry, stone, brick and concrete as well as to steel and timber. Open-cell is specified on timber and board substrates only. The substrate is recorded at survey and the system follows it.
Will it stop my walls running with water?
If the water is condensation, yes: the face the room air touches becomes the foam, above the dew point, and the laps and fixings are closed. If water is coming in at the base or through a damaged sheet, that is repaired first.
Do I lose floor space?
Very little. The layer is applied to the wall's own profile at the specified depth, without battens or a cavity. Where a lining follows, that is specified with you; where it does not, the foam is left as the finished face or coated.
How do you prove it was done properly?
Applied thickness is measured and recorded, coverage is logged, and the evidence is compiled into a QA record handed over at completion.

Project records

Where we have done this before.

All project records
Project record29 schools across Hampshire and Berkshire150 mm of open-cell to the flat roofs, cavity walls filled at several.Read the record

The next step

Your walls.
Your brief.
A specialist.

If you already know the thickness or U-value you need, we price to it and confirm it is right; if not, we work it out with you. Tell us what the walls are built from, what runs down them in winter and what the space is used for. Photographs of the inside face are the most useful thing you can send.

Start a project brief Send photographs first

Or call . Enquiries received before 3pm on a working day are contacted the same day. After 3pm, the next working day. We understand your project before we price it.