Caulk
Caulk is filler material commonly used by decorators. Most caulks are more rigid than sealants, but more flexible than other fillers when they dry and can be used where movement or leakage can occur - as long as significant expansion or contraction is not anticipated.
Historically, caulk was made from fibrous materials that could be driven between boards, pipes and so on to make them waterproof. Rope caulks are still available and are primarily used to reduce drafts, and sound transmission, especially around windows.
Modern caulk is also waterproof. It is typically made from acrylics, vinyl or silicone. These materials dry quickly and remain relatively flexible. It can be used to close small gaps and crevices. It prevents air, insects, rodents and dust from compromising the integrity of seals, spaces and structures.
Acrylic caulk can be painted after it has dried completely. However, painted caulk can crack if it is applied in temperatures lower than four degrees Celsius. Silicone caulk cannot be painted.
Caulk is generally sold in cartridges that can be inserted into caulking guns. This technique helps to control the application process. If spills and smears occur during the process, they can be cleaned up with water rather than solvents.
It is possible to caulk over old acrylic caulk, unless the old caulk is oily, dirty or has deteriorated significantly (in which case, the new caulk will not adhere). Caulk should not be applied over old caulk that is wet or has mould or mildew.
[edit] Related articles on Designing Buildings
Featured articles and news
What they are, how they work and why they are popular in many countries.
Plastic, recycling and its symbol
Student competition winning, M.C.Esher inspired Möbius strip design symbolising continuity within a finite entity.
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.

























Comments
[edit] To make a comment about this article, click 'Add a comment' above. Separate your comments from any existing comments by inserting a horizontal line.