Porous
The word ‘porous’ refers to materials that include voids through which liquids or gasses may pass. Porosity is the volume of such voids relative to the overall volume of the material.
The SuDS Manual (C753), published by CIRIA in 2015 defines porosity as ‘The percentage of the bulk volume of a rock or soil that is occupied by voids, whether isolated or connected.’
A porous surface is: ‘A surface that infiltrates water to the sub-base across the entire surface of the material forming the surface, for example grass and gravel surfaces, porous concrete and porous asphalt.’
Porous asphalt is: ‘An asphalt material used to make pavement layers pervious, with open voids to allow water to pass through (previously known as pervious macadam).’
A porous pavement is: ‘A permeable surface that allows water to infiltrate across the entire surface material through voids that are integral to the pavement.’
NB Technical paper 35: Moisture measurement in the historic environment, published by Historic Environment Scotland in 2021, defines porosity as: ‘A measure of the total amount of void space in a material, usually expressed as a percentage (%).’
Assessing risks in insulation retrofits using hygrothermal software tools, Heat and moisture transport in internally insulated stone walls, by Joseph Little, Calina Ferraro and Beñat Arregi, published by Historic Environment Scotland in 2015, defines porosity as the: ‘Fraction of airspace within a material, often expressed as cubic metres of air per cubic metre of material (m3/m3) or a percentage of the total volume which is composed of air.’
[edit] Related articles on Designing Buildings
Featured articles and news
Do you take the lead in a circular construction economy?
Help us develop and expand this wiki as a resource for academia and industry alike.
Warm Homes Plan Workforce Taskforce
Risks of undermining UK’s energy transition due to lack of electrotechnical industry representation, says ECA.
Cost Optimal Domestic Electrification CODE
Modelling retrofits only on costs that directly impact the consumer: upfront cost of equipment, energy costs and maintenance costs.
The Warm Homes Plan details released
What's new and what is not, with industry reactions.
Could AI and VR cause an increase the value of heritage?
The Orange book: 2026 Amendment 4 to BS 7671:2018
ECA welcomes IET and BSI content sign off.
How neural technologies could transform the design future
Enhancing legacy parametric engines, offering novel ways to explore solutions and generate geometry.
Key AI related terms to be aware of
With explanations from the UK government and other bodies.
From QS to further education teacher
Applying real world skills with the next generation.
A guide on how children can use LEGO to mirror real engineering processes.
Data infrastructure for next-generation materials science
Research Data Express to automate data processing and create AI-ready datasets for materials research.
Wired for the Future with ECA; powering skills and progress
ECA South Wales Business Day 2025, a day to remember.
AI for the conservation professional
A level of sophistication previously reserved for science fiction.
Biomass harvested in cycles of less than ten years.
An interview with the new CIAT President
Usman Yaqub BSc (Hons) PCIAT MFPWS.
Cost benefit model report of building safety regime in Wales
Proposed policy option costs for design and construction stage of the new building safety regime in Wales.
Do you receive our free biweekly newsletter?
If not you can sign up to receive it in your mailbox here.