What is lime and why does it matter?
Lime has been used as a building material for thousands of years, dating back to ancient civilisations such as the Romans. Lime is a natural material derived from limestone, valued in construction for its breathability, flexibility and long-lasting performance in mortars, renders and plasters. Lime is the binding agent that kept our built heritage together — and continues to be the material of choice for conservation and sustainable construction today.
A building material as old as civilisation Types of lime
Not all lime is the same. Understanding the differences helps you choose the right product for your project.
Natural Hydraulic Lime (NHL)
NHL sets through a chemical reaction with water (hydraulic set). It is available in three grades: NHL 2 (feebly hydraulic), NHL 3.5 (moderately hydraulic), and NHL 5 (eminently hydraulic). Higher numbers indicate greater strength and water resistance, but less flexibility.
Non-Hydraulic Lime (Lime Putty)
Lime putty sets slowly through carbonation — absorbing CO₂ from the air. It remains workable for longer and produces a softer, more flexible finish ideal for delicate historic masonry and interior plasterwork.
Choosing the right grade
NHL 2 — soft and porous stones, sheltered locations, fine interior work
NHL 3.5 — general pointing, rendering, and plastering in exposed conditions
NHL 5 — hard masonry, below-ground work, high-exposure locations
Lime putty — conservation work, delicate historic masonry, fine finishes, lime washes
Lime vs cement
Cement is harder and less permeable than lime, which can trap moisture in older buildings and cause significant damage through spalling and salt crystallisation. Lime breathes — it allows moisture to migrate through the wall and evaporate, keeping the building dry from the inside out.
Traditional craft, modern performance
Modern lime products blend centuries of knowledge with contemporary manufacturing standards. Whether you are repointing a Tudor manor or rendering a Passivhaus, there is a lime product engineered for the task.
The lime application process
Prepare the substrate
Clean out old mortar to the required depth, remove loose debris, and dampen the substrate to prevent the lime from drying too quickly.
Mix to the right consistency
Follow the product data sheet for mixing ratios. Lime mortars should be mixed to a stiff, workable consistency — not soupy.
Apply and work the surface
Apply in layers as recommended. For pointing, work firmly into the joint. For render, scratch back the first coat before the second is applied.
Protect and cure
Cover with hessian for at least 72 hours. Keep moist in hot or dry weather. Protect from frost.
Frequently Asked Questions
Do you offer bulk or pallet delivery?
Yes — we offer pallet delivery for larger orders, which is the most cost-effective way to order multiple bags. Pallet orders are delivered via a tail-lift vehicle; please ensure there is suitable access and ground conditions at your site.
For smaller orders, standard courier delivery is available.
What is your returns policy?
We accept returns of unused, undamaged products in their original packaging within 14 days of purchase. Please contact us before returning any items.
Opened bags or products that have been mixed cannot be returned. All Lime Green products are non refundable. For full details, please see our Refund & Returns Policy page.
What is the Warmshell Woodfibre Insulation range?
Warmshell is Lime Green's range of natural woodfibre insulation boards, designed for use in traditional and modern construction. Woodfibre insulation is vapour-open, sustainable, and offers excellent thermal and acoustic performance.
It is particularly well suited to use alongside lime plasters and renders, creating a fully breathable envelope for heritage buildings and low-energy new builds.