Developing an appropriate specification for a traditional building, retrofit project or low-energy construction can be complex. Materials must be considered as part of a complete building system rather than selected in isolation.
Roundtower’s Specification Support Service supports architects, designers, contractors and homeowners in developing practical floor, wall and roof build-ups using compatible, vapour-open and moisture-conscious materials.
Our team can assist from the early design stage through to the preparation of detailed material build-ups, product recommendations and supporting thermal or hygrothermal analysis.
How We Can Help
We provide specification assistance for a wide range of new-build, renovation and conservation projects, including:
- Internal wall insulation systems
- External wall insulation systems
- Insulating lime plaster specifications
- Traditional lime render and plaster systems
- Solid stone and brick wall upgrades
- Limecrete floor build-ups
- Breathable floor insulation systems
- Timber-frame wall and roof assemblies
- Wood-fibre insulation systems
- Calcium silicate insulation systems
- Vapour control and airtightness layers
- Roof insulation and ventilation strategies
- Mineral paint and breathable finishing systems
- Repair mortars, renders and associated conservation materials
Our recommendations consider the complete build-up, including the existing substrate, exposure conditions, insulation, airtightness, vapour control, finishes and junction details.
Support for Architects and Designers
We regularly assist architects and building designers with the development of project-specific specifications.
This may include:
- Reviewing proposed wall, floor or roof constructions
- Recommending compatible materials and systems
- Preparing outline material specifications
- Advising on appropriate insulation thicknesses
- Reviewing vapour-control and airtightness strategies
- Identifying potential moisture risks
- Providing product technical data
- Assisting with U-value targets
- Advising on detailing at reveals, floors, roofs and junctions
- Supporting tender documentation and contractor queries
Our objective is to provide clear and practical guidance that can be incorporated into the project design and developed by the appointed design team.
Support for Traditional and Historic Buildings
Traditional solid-wall buildings require a different approach from modern cavity construction.
A specification that performs well in a modern building may not be suitable for older stone or brick walls, particularly where the structure relies on vapour-permeable materials and capillary drying.
When developing a specification for a traditional building, we consider factors such as:
- Existing wall construction and thickness
- Stone, brick or block type
- Mortar and plaster condition
- Moisture sources
- Driving-rain exposure
- Ground levels and drainage
- Internal heating and ventilation
- Salt contamination
- Material vapour permeability
- Capillary moisture transport
- Drying potential
- Thermal bridging and surface-temperature risk
This helps reduce the likelihood of selecting materials that could trap moisture or place unnecessary stress on the existing building fabric.
WUFI Hygrothermal Analysis
Where a more detailed assessment is required, Roundtower can provide WUFI hygrothermal analysis.
WUFI modelling assesses the movement of heat and moisture through a building element over time. Unlike a simple steady-state condensation calculation, it can consider changing internal and external conditions, rainfall, solar radiation, moisture storage, vapour diffusion and liquid moisture transport.
WUFI analysis may be particularly useful for:
- Internal insulation on solid masonry walls
- Exposed or moisture-sensitive elevations
- Historic stone and brick construction
- Complex roof and timber-frame assemblies
- Vapour-open insulation systems
- Projects where condensation or moisture accumulation is a concern
- Comparing alternative insulation or finishing systems
- Assessing drying potential following retrofit works
The analysis can help identify whether moisture is likely to accumulate within an assembly and whether the proposed construction is expected to reach a stable long-term condition.
WUFI modelling should be treated as a design-support tool rather than a guarantee of building performance. The accuracy of the results depends on the quality of the material data, climate assumptions, boundary conditions and information available about the existing building.
U-Value Modelling
We can also calculate and compare the estimated thermal performance of proposed floor, wall and roof build-ups.
Our U-value modelling service can help clients:
- Compare different insulation products
- Assess alternative insulation thicknesses
- Estimate improvements over the existing construction
- Support compliance and design decisions
- Balance thermal performance against available space
- Compare vapour-open retrofit options
- Understand the effect of thermal conductivity and material thickness
Where appropriate, we can model several options so the client or design team can compare thermal performance, build-up thickness and material suitability.
U-value calculations assess heat loss under standardised conditions. They do not, on their own, assess moisture movement, thermal bridging, workmanship, air leakage or real-world building operation. For moisture-sensitive constructions, a U-value calculation may therefore need to be supported by additional hygrothermal assessment.
Floor Specification Assistance
We can assist with the development of breathable and insulated floor build-ups for traditional and modern buildings.
This may include advice on:
- Limecrete floors
- Foamed-glass aggregate insulation
- Radon protection
- Geotextile and separation layers
- Underfloor heating
- Floor finishes
- Junctions with solid masonry walls
- Moisture movement through floors
- Finished floor levels
- Load and compaction requirements
Each floor specification must be considered in relation to the building, ground conditions, structural requirements and proposed use.
Wall Specification Assistance
Our wall specification service covers both thermal upgrades and traditional repair systems.
Typical projects include:
- Internal wall insulation
- External wall insulation
- Insulating lime plaster
- Wood-fibre insulation
- Calcium silicate insulation
- Lime plaster and render
- Repointing and masonry repair
- Vapour-control layers
- Airtightness systems
- Breathable paints and finishes
We can help assess the advantages and limitations of different systems and identify which approach is most appropriate for the wall construction and project objectives.
Roof Specification Assistance
Roof build-ups require careful consideration of insulation, airtightness, vapour control, ventilation and moisture safety.
We can provide guidance on:
- Insulation between, above or below rafters
- Wood-fibre roof insulation
- Flexible insulation between timbers
- Vapour-control layers
- Intelligent vapour-control membranes
- Airtightness detailing
- Breather membranes
- Ventilated roof voids
- Service cavities
- Internal finishes
- Roof-to-wall junctions
The correct solution will depend on whether the roof is pitched or flat, ventilated or unventilated, and whether the building is new, existing or traditionally constructed.
A Project-Specific Approach
There is no single specification that is suitable for every building.
Our advice is based on the information available for the individual project, which may include:
- Drawings and construction details
- Site photographs
- Existing wall or floor build-ups
- Material data sheets
- Survey information
- Moisture readings
- Project location and exposure
- Proposed heating and ventilation
- Planning or conservation requirements
- Required thermal performance
Where important information is unavailable, we will identify the assumptions being made and may recommend further investigation before a final specification is adopted.
Who Is This Service For?
Our Specification Assistance Service is available to:
- Architects
- Architectural technologists
- Engineers
- Conservation professionals
- Building designers
- Energy consultants
- Contractors
- Self-builders
- Homeowners
- Property developers
- Public bodies and heritage organisations
We can assist with both small domestic projects and more complex commercial, conservation or institutional buildings.
Discuss Your Project With Roundtower
If you are developing a floor, wall or roof specification, contact the Roundtower technical team with your drawings, photographs and available project information.
We can review the proposed construction, recommend appropriate materials and advise whether U-value modelling or WUFI hygrothermal analysis would be beneficial.
Contact Roundtower today for practical specification assistance for breathable, energy-efficient and traditionally constructed buildings.
