The UK’s Best Wall Mending Agents For Cracks In Your Home

  • We review 5 of the best products in the UK.
  • Easily mend walls & ceilings in your home with our top picks!
concrete wall damaged with cracks

Cracks in walls and ceilings are not only unsightly, they are often insidious. They can lengthen, widen, or deepen, causing grave damage. But such damage can be forestalled by that proverbial stitch in time that saves nine: an effective wall-mending agent and filler.

Mending and filling small cracks and holes in walls, and filling in seams and gaps between different architectural elements can almost be classified as an ‘Entry-Level DIY’ job. Quite an array of pre-prepared high-tech fillers and compounds are available and these make what used to be a technical and tedious job something that a newbie can tackle with confidence.

Offered in tubes and tubs, powder and paste, these fillers are also made of quite a variety of chemical compounds. Because these products are so varied, each one is best for, and even specially formulated for, specific applications. However, this specialisation can bring about immense satisfaction or deep disappointment on part of the user depending on whether you choose a product that is exactly right for your needs…or one that is well wide of the mark!

Underneath we recommend five highly-rated wall mending agents and fillers. Though all of them are very fine products, each has its particular qualities and strengths.

You can choose the right product and utilise its qualities and strengths to your best advantage by asking yourself some questions. Do you want to:–

  • Repair cracks and holes in drywall or fill seams in and around skirting and flooring?
  • Apply two or three applications for a gradual fill or try to effect the repairs in one shot?
  • Have the filler set firm and hard or stay semi-hard and flexible?
  • Get a finish that will take a proper coat of paint or only a basic white filler?
  • Simply squeeze the filler out of a tube or use a caulking gun or sealing gun?
  • Repair interior walls and ceilings or seal exterior rooflines and leaks?
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These questions are elaborated in our review below as we sift and sort through various products and their respective pros and cons to help you quickly select the one that scores a bulls-eye for you and your needs.

Best Pick For Small Holes and Hairline Cracks

Multi-Purpose Polyfilla |

Polycell’s Polyfilla is a versatile, all-purpose crack and gap filler that is ideal for small holes and hairline cracks in plaster, sheetrock, drywall, and such. Offered here in a 330-gramme tube, it is dead easy to apply and is also ideal for rank beginners. At the same time, this product is trusted by pros as well and is also sold in professional sizes and packaging such as one-kilogramme tubs. 

Polyfilla is surely the ‘go-to’ product when you need to fill small holes left behind by removed screws and hooks, and for filling those unsightly cracks and gaps where walls meet ceilings. After Polyfilla has dried, you can build it up with a second layer or sand it down. Though this is not a grout, it can even repair tile.

It dries fast to a clear white and can be painted over in a few hours. It can also even be drilled into after drying as it is resistant to cracking and shrinking. But because it dries so fast, beware of leaving the tube uncapped for too long!

One niggle to watch out for: tubes of some batches contain filler of a sub-par or gritty consistency probably as a result of improper or insufficient mixing, or because of separation. If you get one of those, simply buy another from some other source and you should be fine.

Polyfilla tubes should not be viewed as a cost-effective solution for contractors who fill large, long cracks; it is an inexpensive buy for DIYers looking to maximise convenience and minimise headache. Professionals can make good use of Polyfilla tubs.

☺ Pros

  • Possibly the easiest and most convenient filler to apply.
  • Dries quite quickly to a firm, hard material.
  • Tried and trusted even by professionals.

☹ Cons

  • The filler in some batches/tubes is either not fully and properly mixed, or has separated.
  • Do not leave the tube of this quick-drying filler open!

Best For Deep Holes And Cracks

Everbuild One-Strike Filler |

Although Everbuild One Strike works very well for hairline cracks, where it really plants a ‘best in class’ flag is in deep filling and mending in one shot – or in ‘one strike.’ It is rated to fill and repair up to 75 millimetres in a single application. Besides the one-litre tub linked-to here, this product is also available in 250 gramme, 2.5 litre, and 5 litre sizes.

It is best to apply this product in that eponymous ‘one strike’ and not to over-work its application. Slap on, push in, and smooth over.

One Strike repairs not only cracks but is even good for filling gaps and holes, and does so in all manner of masonry – stone, brick, plaster, and more.

It is so easy and quick to apply that one would never expect the eventual repair-job and finish to be as spanking good as it turns out. It is so surprisingly effective that one may have to resist the temptation to get carried away and improperly use it for structural repairs. Even when applied thickly it does not sag.

This product, and consequently also its container, are super-lightweight and deceptively so. It is one of the lightest-weight filling compounds and, compared to competing products, its consistency is thinnish – similar to foam or mousse.

Depending on how well it is packed in and the ambient temperature, it may set solid and hard – or not. Your technique and environmental factors influence how well this product works.

It dries in about 30 minutes to a smooth white finish providing a perfect surface for painting over or wallpapering. Though it virtually never needs sanding so long as it is applied properly, if you opt to sand it you can make a good finish even better.

Do not neglect to close the tub quickly and properly else you will find your One Strike has unexpectedly hardened!

This product contains benzisothiazolone which is known to be a chemical allergen.

☺ Pros

  • Fills fairly deep cracks and holes in a single application.
  • Dries and sets so well and smoothly that sanding is usually superfluous.
  • Available in a variety of sizes and configurations, to suit everyone from the homeowner with the occasional job to a professional outfit.

☹ Cons

  • One of its ingredients, benzisothiazolone, may trigger allergies.
  • Those who have used conventional products may find this foamy, mousse-like product difficult to apply or get used to.

Best Exterior Filler

Everbuild Everflex Weather Mate |

Everbuild Everflex Weather Mate is sold in 295-millilitre canisters to be used in a caulking gun or sealant gun. It is available in Black, White, and Clear finishes.

Impervious to weather fluctuations, it is rated to withstand a very wide range of temperature, from -25 to 95 degrees Centigrade.

This exceptionally versatile, no-fuss product adheres to numerous materials including bitumen, asphalt, lead, and PVC. However, it is tailor-made for roofline applications and really sets the standard in sealing leaks in, and waterproofing, roofing, piping, guttering, and conservatories, and sealing cracks in stone and slate tiles. It fills cracks and gaps up to 5 millimetres wide.

This advanced-compound isocrylic product can be applied to surfaces that are damp, and it can – most impressively – even be applied during wet weather. For this reason it is an excellent choice to keep on hand for plugging small leaks in emergencies.

It is the consistency of adhesive glue, and is easy to smooth, work and shape with a moist finger.

So is Weather Mate a filler? Is it a sealant? We have a hung jury so let’s call it a ‘fillant’! Whatever one may call it, it is virtually impossible to use for any interior jobs because this product is very strong-smelling – and the smell is distinctly unpleasant.

Everbuild’s ‘Everflex’ does not set hard; it is permanently semi-flexible by design to accomodate contraction and expansion in exterior joints and seams, and also to account for the different rates of expansion and contraction of the disparate materials that it is meant to bond.

It can be painted over after it is cured in about 24 hours.

☺ Pros

  • Can’t be beaten for sealing leaks and can even be applied on damp surfaces and in wet weather.
  • Bonds to and makes a seal between diverse types of materials.
  • Effectively fills gaps of widths up to an impressive 5 millimetres.

☹ Cons

  • Sold only in canisters meant for caulking guns.
  • Strong, unpleasant odour eliminates the possibility of using it indoors.

Best Quick Dry Filler

Caulk Once |

Caulk Once is a decorator’s caulk available in 295-millilitre canisters for use in a caulking gun.

This product is billed as a caulk for ‘skirting boards, ceiling cornices, window and door frames,’ and ‘fixtures adjoining walls.’ In general, it is a good choice if you have interior cracks and gaps that have to be filled or seams and crevices that need to be sealed. It is also useful for repairing small cracks in plaster.

It really comes into its for sealing seams between different materials, not only because of its capability to adhere to different materials, but, also because it retains a degree of flex thereby allowing disparate materials to expand and contract at their respective rates without deforming or breaking.

See Also
a student room with items hung on the wall

Polymer-based Caulk Once exhibits very little shrinkage and very low slump. A big plus point for interior use is that it is virtually odourless. The just-right viscosity makes it simple to apply with a caulking gun and – to cap it off – it is easy to shape and smooth

Though it is rated to dry and cure in only 15 minutes, this is a little optimistic. To be on the safe side, allow two hours to dry. Paint over or paper over it after about four hours. As a decorator’s caulk, after curing Caulk Once offers an excellent surface – white, clean, and firm – for painting over with gloss, emulsion, or any other type of finish, though you should first apply a coat of primer.

At its price Caulk Once is a very good value.

☺ Pros

  • After curing it provides an excellent surface that is white, clean, and firm.
  • Easy to shape and smooth, and quick to dry.
  • Best choice for aesthetic interior filling of gaps and seams.

☹ Cons

  • Flexible by design, this property makes it less than optimal to fill cracks in plasterboard.
  • Not a versatile filler that can do a variety of repair jobs.

Best Value Pick

Everbuild Flexible Decorators Filler |

Everbuild Flexible Decorators Filler, an acrylic-based decorator’s caulk, is available in 290-millilitre cartridges for using with caulking guns or sealant guns.

As the product’s name suggests, after application it remains permanently flexible which makes it perfect for ‘filling cracks that are subject to further movement such as between a skirting and a wall or a window frame and a wall.’ It is a smart choice to fill seams between different types of materials such as sheetrock and vinyl.

It is resistant to slumping and cracking. For the most part it dries to a bright white and retains its whiteness.

That qualifier ‘for the most part,’ is made out of prudence: Everbuild’s quality control appears to be rather lax: the filler from some batches and cartridges stinks to high heaven while others do not dry to a true white and still others are prone to slumping. However, if you get a canister with good filler, you’ll be chuffed out of your mind, given the price of this thing. Yes, what you get depends on the luck of the draw but at this product’s ultra-low price it’s a draw you can afford to make.

This product can be seen as an alternative to Caulk Once as these products share several properties. If you have a lot of small gaps and seams to fill, want the convenience of a pre-prepared filler and a cartridge that you can load in a gun, are interested solely in functional filling and do not care much about prettification and cosmetic aspects, then budget-priced Flexible Decorators Filler is the way to go.

☺ Pros

  • Ideal for filling and sealing gaps and seams between disparate materials inside the home.
  • Easy to apply with a caulking gun, and quick drying.
  • Inexpensive product gives you the best bang for your buck.

☹ Cons

  • Flexible by design, this property makes it less than optimal to fill cracks in plasterboard, etc.
  • Dodgy quality control means that you may get stuck with a cartridge with poor-quality filler.

How To Apply Wall Filler

Essentially you have three methods by which to apply wall filler. You can do it the hands-off homeowner way by squeezing filler from a tube, do it the old-fashioned way by buying it in powdered form, mixing a batch and applying it with a flexible trowel, or you can do it the modern way by loading a cartridge in a caulking gun and gunning the filler.

No matter which method you use, the crack has to be deep and wide enough – but not so deep or wide that using a filler would be an exercise in futility. If the crack is too thin and narrow, you will actually have to open it up!

When you apply any filler or sealant, you have to make sure that the crack, seam or gap is thoroughly filled and the filler is ‘worked’ and smoothed. Applying wall filler is not a complicated process but it requires some know-how and the use of good technique. For particulars, see our instructional article How To Repair Cracks in Internal Plaster Walls and Ceilings.

How To Fill a Hole in a Wall

You may need to fill either of two kinds of holes: first, a hole left behind by a nail or screw, and second, a somewhat bigger hole caused by damage. Note that if a large hole goes clear through the plasterboard or sheetrock, then you cannot simply ‘fill’ it; you have a bigger repair job on your hands.

For the first type of hole, clean it out with a stiff small paintbrush or toothbrush. If the hole is really tiny, open it up a bit. Take a tube of Multi Purpose Polyfilla or comparable product and directly squeeze it into the hole and push it in and smooth it with your finger, or bead it on your finger and work it into the hole, and smooth it so it is flush with the wall. Allow it to dry.

For the second type of hole, you will need a stiff paintbrush and/or a handheld vacuum cleaner with a narrow crevice attachment, a flexible filler trowel or plasterer’s float, Everbuild One Strike Multi Purpose Filler or similar product, some P120 sandpaper, and some PVA and another paintbrush.

Clean out the loose dust and debris from the hole by brushing it clean with a stiff paintbrush or vacuuming it out; you could even do both for a thorough job. Scoop up a blob of One Strike on the trowel or float and apply it by pushing it into the hole, filling the hole, and smoothing over the filler. Scrape off any excess and run the trowel or float along the edges where the filler comes over the wall to smooth it down. Allow the filler to dry. One Strike does not require sanding but you can give it a light touch up with P120 if you find it desirable. As the last step, apply a coat of PVA to your repair job.

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