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As our local weather continues to alter, flooding is more and more a priority for owners.
For self-builders, flooding can have severe implications, even earlier than a brick is laid. Should you’re shopping for land, flood threat isn’t only a matter of security, it’s a basic a part of the planning course of. Get it incorrect, and you might face delays, further prices, or refusal of your utility. However with the precise info {and professional} help, constructing in a flood zone can nonetheless be attainable.
This text explains what a flood zones are, the consequences of various kinds of flooding, and what planning guidelines you’ll have to know should you discover a plot is in a flood zone. It additionally explains the design choices that can defend your property, and what help is accessible if issues go incorrect.
What’s a flood zone?
In England, flood zones are outlined by the Atmosphere Company and replicate the chance of flooding from rivers or the ocean.
There are three major zones, from 1 to three classes, with the flood threat starting from low to excessive respectively. Zone 3 is additional cut up into 3A and 3B, with A being land that’s developable with the precise mitigations. B covers areas that function pure flood storage – and comes with probably the most extreme restrictions.
It’s essential to know that these zones don’t keep in mind all sorts of flooding, and that’s the place self-builders typically come unstuck.
Sorts of flooding
After we consider flooding, we regularly image rivers breaking their banks or storm surges washing in from the ocean, however this isn’t the complete extent of flooding that happens.
River flooding occurs when rivers and streams can’t deal with the quantity of water, normally after heavy rainfall.
Coastal flooding is brought on by excessive tidal circumstances and storm surges.
Floor water flooding occurs when rainwater can’t drain away rapidly sufficient – one thing that’s turning into frequent as city areas increase, and extra floor is roofed by impermeable surfaces.
Groundwater flooding occurs when underground water ranges rise and seep into buildings.
The best way to examine the flood threat
The perfect place to start out is the Atmosphere Company’s interactive flood map, which reveals flood zones, floor water threat, and historic flooding. It’s free and simple to make use of and also you simply want a postcode.
Native planning authorities (LPA’s) even have their very own Strategic Flood Danger Assessments (SFRAs), which might reveal vulnerabilities not proven on nationwide maps. To make sense of this info, particularly when shopping for a constructing plot, its finest to fee a Flood Danger Report from a specialist guide.
Why construct in a flood zone?
It’s fairly frequent to construct in flood threat zones for a wide range of causes.
Planning insurance policies typically require new houses to be constructed inside current settlements and until the chance of flooding is excessive, improvement shall be allowed below sure circumstances akin to changing an current home. In some circumstances, the land might have an historic planning permission that was granted earlier than the chance of flooding was recognized.
While planning insurance policies might not at all times prohibit improvement, it is nonetheless essential to ask if constructing in a flood threat space is a good suggestion? Likewise questions also needs to be requested when contemplating shopping for a home in a flood threat space.
After all, when searching for land, it is best to look the place flooding will not be an issue, nonetheless, should you already personal the land you may not have any different. It’s due to this fact important that you already know the dangers and embrace mitigations to maintain your property secure.
Should you already personal land you already know is vulnerable to flooding, you have to absolutely perceive the chance of constructing on it(Picture credit score: Getty Photos)
Planning guidelines for constructing in flood zones
Should you’re planning to construct in a flood zone – particularly Zones 2 or 3 – you’ll face stricter planning controls. In these increased threat zones, LPA’s will apply a ‘sequential check’ which asks whether or not the event may fairly be positioned in a lower-risk zone. If it will possibly’t, they’ll grant consent on the idea that the broader sustainability advantages outweigh the flood dangers and that these dangers might be managed.
That is the place a Flood Danger Evaluation involves show the mitigations required and fulfill the exception check.
A Flood Danger Evaluation (FRA) is a key a part of a planning utility for brand new developments. The FRA should show how the event will stay secure over its lifetime, how flood threat shall be managed, and the way it gained’t make flooding worse elsewhere. It considers the obtainable flood threat information and assesses the location ranges in opposition to forecast flood ranges.
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Designing a construct for a flood plain
Constructing in a flood threat zone requires good high quality design to incorporate the important mitigations and supply flood resilience.
When constructing a brand new house, the most effective start line is to boost the ground ranges above anticipated flood ranges. This largely entails build up the bottom flooring slab. If flood water displacement is required, it is perhaps mandatory to construct on stilts or permit the flood water to enter the substructure. It will require drainage techniques to have non-return valves to forestall floodwater backing up via bogs and sinks.
When extending or changing current buildings, elevating your complete flooring degree is probably not attainable so contemplate split-level flooring plans to raise important dwelling areas. The problem is then to construct a house that may stand up to flooding by resisting water and recovering rapidly, following a flood.
Sturdy development supplies are important as they drastically cut back the influence of a flood and make restoration a lot sooner. Concrete, bricks, and cement-based render all carry out effectively in moist circumstances. Timber can also be an excellent because it rapidly reverts to its authentic situation as soon as flood water recedes.
Internally, ceramic flooring tiles and closed-cell insulation will restrict injury as they gained’t take in water. The bottom line is to keep away from supplies that change into broken or absorb water, like chipboard, plasterboard or laminate flooring. It’s additionally a good suggestion to boost electrical sockets and home equipment effectively above the anticipated flood degree to restrict the chance of harm.
Flood readiness and mitigation
Even with a well-designed home, it is nonetheless smart to arrange for the worst. Signing up for flood alerts is a should, so register for alerts from the Atmosphere Company. Have sandbags readily available to reply rapidly throughout a flood occasion. Extra subtle choices like flood boards, airbrick covers, and door boundaries provide higher ranges of safety.
If your property is broken by flooding, examine should you’re eligible for the Construct Again Higher scheme. The scheme supplies as much as £10,000 on high of reinstatement prices to put in flood prevention measures. This might pay for putting in flood doorways, elevating electrics, or changing flooring with extra water resistant choices.
Insurance coverage and monetary implications
In a high-risk space, insurance coverage is probably not obtainable or insurers might provide cowl however with excessive premiums and huge excesses. To assist, the federal government and the insurance coverage business arrange Flood Re, a scheme that makes reasonably priced flood insurance coverage for qualifying houses.
However – and this can be a huge however – Flood Re solely applies to current properties constructed earlier than 1 January 2009. Should you’re constructing a brand-new home in a flood zone, you most likely gained’t qualify.
This all signifies that you’ll want to seek out specialist insurance coverage, which may price considerably greater than an ordinary coverage. And should you’re planning to promote the property later, restricted insurance coverage choices can have an effect on saleability.
FAQs
Can I construct in a flood zone if I increase the home above the flood degree?
Presumably, however planning consent will nonetheless rely on the sequential and exception assessments and a Flood Danger Evaluation shall be wanted to show security and threat mitigation.
Will constructing on stilts imply I don’t want flood insurance coverage?
Probably not. Insurers have a look at postcode, historic information, and Atmosphere Company classifications. Even when your own home is elevated, they could nonetheless contemplate the realm excessive threat.
Is constructing in a flood zone ever a good suggestion?
Most often, it’s higher to keep away from it. However if in case you have no different, otherwise you’re changing or extending and current constructing, it may be executed with the precise precautions and practical expectations.
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