How to Insulate a Cold Wall From The Inside

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Key Takeaways:

  1. Critical Role of Wall Insulation: The content emphasizes the significance of insulation in residential structures, focusing on three main approaches: Cavity Wall Insulation, Internal Wall Insulation, and External Wall Insulation.
  2. Energy Efficiency through Solid Wall Insulation: The primary focus is on the substantial heat dissipation through external walls, especially in older homes. The discussion highlights the drawbacks of relying on a thin plaster layer and introduces insulation options for solid walls, both internal and external.
  3. Advantages and Considerations of Internal Wall Insulation: The advantages of internal wall insulation are presented, including cost efficiency, concealing imperfections, simplified installation (especially for self-installation), suitability for certain building types, and considerations for conservation areas.

Insulation measures within residential structures are critical to arresting heat dissipation, fostering interior warmth and yielding substantial energy conservation benefits. Notably, three distinct approaches to insulating solid walls merit consideration:

1. Cavity Wall Insulation: This methodology involves infilling the wall cavity with insulation material. This technique is the most expedient, cost-effective, and minimally disruptive option when a cavity exists.

2. Internal Wall Insulation: In this context, the internal surfaces of exterior walls are affixed with insulation layers. It is imperative to discern that this method pertains exclusively to exterior walls and not interior partitions. This approach is commonly preferred for solid walls owing to its comparative cost-effectiveness and efficacy, although it can also be deemed suitable for cavity walls under specific circumstances.

3. External Wall Insulation: This variant encompasses the application of insulation materials on the external façade of a dwelling. Such a measure contributes to bolstering energy efficiency and thermal retention.

For a succinct overview of the distinctions between these insulation techniques, a concise elucidation is accessible at “Be Energy Smart.” The ensuing discussion will be dedicated to the intricacies of Internal Wall Insulation, which encompasses the insulation of external wall interiors. It should be underscored that this pertains to the walls facing the exterior environment rather than the internal divisions within the property. This approach is typically favoured for solid walls, a preference rooted in its cost-efficiency and superior efficacy. In select scenarios, it can also be employed for cavity walls.

Enhancing Energy Efficiency through Solid Wall Insulation

Inefficient insulation contributes significantly to heat loss in residential properties, with a substantial portion, up to 45%, emanating from external walls. This concern is particularly pronounced among the 10 million homes in the UK lacking cavity walls. Notably, the Energy Saving Trust underscores the potential for substantial savings, averaging around £455 annually, for a typical detached home.

While due emphasis is rightly placed on loft insulation, double glazing, and energy-efficient lighting, the substantial heat dissipation through the walls of older dwellings constructed without modern insulative standards remains a substantial issue.

The primary defence against such heat loss often amounts to a mere 13mm plaster layer, occasionally accompanied by two coats of paint or a layer of wallpaper. For structures with solid walls or inaccessible cavities, insulating the inner or outer surface of external walls presents a viable solution. Notably, due to its complexity, external wall insulation is generally a task best entrusted to professional firms.

On the other hand, internal insulation of external walls presents a feasible do-it-yourself option in specific scenarios. Those interested in pursuing this route can proceed with confidence. A qualified insulation installer can be easily located for those seeking professional assistance.

Should your residence deviate from conventional brick, block, or stone construction, such as timber frame or metal structures, alternative insulation approaches must be considered. Engaging with the National Insulation Association is recommended for tailored guidance in such cases.

In conclusion, prioritising energy efficiency through solid wall insulation is paramount for homeowners and society. Addressing the inadequacies in insulation by adopting suitable measures fosters substantial economic savings and aligns with contemporary environmental imperatives.

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Advantages and Drawbacks of Internal Wall Insulation

When considering the insulation of solid walls, internal wall insulation presents distinct advantages compared to external wall insulation. These benefits encompass:

Cost Efficiency: The cost of internal wall insulation is projected to be approximately £40-£50 per square meter (as of December 2016), constituting roughly half the expense of external wall insulation. Notably, around 60% of this cost pertains to labour, potentially leading to even more substantial savings if a DIY approach is adopted.

Concealing Imperfections: Internal wall insulation obscures cracks and flaws that might manifest on the original plastered walls. This insulation can also effectively mask more significant structural issues; however, addressing such concerns is imperative before the insulation process.

Simplified Installation, Particularly for Self-Installation: The installation process is notably streamlined, mainly when undertaken as a DIY project. Unlike external insulation, there is no requirement for specialised scaffolding, equipment, or skills, including adjustments to eaves and roofing structures.

Suitability for Apartments and Maisonettes: Internal wall insulation is often a pragmatic choice for multi-unit residences such as flats and maisonettes. Internal insulation remains viable when external insulation is unfeasible due to building configuration or lack of consensus among residents.

Conservation Area and Aesthetic Considerations: Internal wall insulation may be the sole option for conservation areas or homes with distinctive architectural character. Conversely, external insulation offers an avenue for transformation for those seeking to alter their home’s appearance.

However, several pivotal factors necessitate consideration before selecting internal wall insulation:

Condensation: An essential consideration is condensation, which may arise when a previously heated wall becomes cooler due to interior insulation. Our comprehensive condensation causes and solutions resource explores this potential outcome.

Preceding Damp and Issues: Before contemplating internal insulation, addressing preexisting damp and structural problems is imperative. Concealing these issues with insulation could lead to subsequent complications. Consult our dedicated project resource for detailed insights into damp causation and remedies.

Space Reduction: A thickness of approximately 100mm is recommended to achieve optimal insulation efficacy. However, this allocation will inevitably reduce the available living space within the room. While alternatives with reduced thickness exist, they involve a trade-off in insulation effectiveness.

Interior Fixture Disruption: Implementing internal insulation necessitates removing and relocating internal fixtures and fittings along the exterior wall. Radiators, light fixtures, and switches must be temporarily removed and reinstated on the new interior surface once the insulation is integrated.

Mounting Challenges for Decorative Items: Fixing heavy items such as televisions or pictures onto insulated walls can pose difficulties, as the insulation needs to provide a robust anchor. Strategic batten placement before securing plasterboards over insulation is a prerequisite for installing kitchen units.

Once an in-depth assessment of the pros and cons of internal wall insulation versus alternative approaches has been undertaken, an informed decision-making process can guide the chosen insulation strategy.

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Choices for Internal Solid Wall Insulation

When exploring internal solid wall insulation, various options come into play, with opinions varying depending on the source. This comprehensive overview aims to encompass the full spectrum of possibilities, acknowledging that some may not align with strict definitions of internal wall insulation.

Four primary options present themselves, ranked in order of ascending efficacy and required effort:

1. Thermal Insulation Wallpaper

2. Insulation Boards

3. Thermal Battens

4. Stud Walls

In the subsequent sections, we will detail these options, outlining their advantages and disadvantages. Initially, let’s focus on the installation process itself.

DIY Installation of Internal Solid Wall Insulation: Step-by-Step Guide

A systematic approach is essential for those considering the self-installation of internal solid wall insulation. The following guide outlines the generic process, encompassing specific variations for different insulation options. Thorough preliminary work, insulation selection, and meticulous installation are crucial to ensure a successful outcome. It is important to note that while the methods outlined can be employed individually, the overall process remains consistent. Specific procedures may diverge according to the chosen insulation variant.

Step 1: Assess Wall Condition Begin by addressing any underlying issues with the wall to be insulated. The wall must be both structurally sound and devoid of dampness. This step is pivotal in avoiding latent complications that could manifest after the insulation is in place, incurring higher costs for resolution.

Step 2: Opt for Suitable Insulation Conduct comprehensive research to determine the most appropriate insulation option for your specific requirements. Consultation with manufacturers is advisable to ascertain the recommended insulation thickness for your application and its impact on wall performance. Enhanced insulation effectiveness may lead to heightened condensation risk due to lower wall temperatures.

Step 3: Strategize for Complex Areas. Devise a strategy to accommodate challenging sections such as window, door reveals, and potential cold bridge zones. Attention to these areas is pivotal for achieving comprehensive insulation coverage.

Step 4: Clear the Wall Surface Remove all fixtures and fittings from the wall, including light fixtures, switches, radiators, kitchen cabinets, skirting boards, and coving. This preparatory step is essential to create a blank canvas for insulation installation.

Step 5: Prepare as Required. Adhere to manufacturer guidelines for preparatory work that complements your chosen insulation solution. Proprietary adhesives might be stipulated for optimal installation, and these recommendations should be meticulously followed.

Step 6: Install Insulation or Build Stud Wall Proceed to install the chosen insulation method or construct a stud wall, dependent on the selected approach. Methodology adherence ensures insulation integrity and effective barrier establishment.

Step 7: Seam Sealing and Finishing Thoroughly seal joints and meticulously execute finishing work, such as plasterboard skimming. These details are instrumental in achieving a polished result.

Step 8: Reinstall Fixtures and Fittings With the insulation in place, reinstall all fixtures and fittings, meticulously following specific installation protocols for each item, including:

  • Light fixtures
  • Switches
  • Kitchen cabinets and wall units
  • Cupboards
  • Radiators
  • Coving, skirting boards, and architrave

Understanding Cold Bridges: Cold bridges are conduits that transfer cold from exterior sections of a wall to warmer interior portions. These areas are prone to condensation buildup. A classic example is cavity wall ties that create cold bridges between outer and inner walls, causing localised cooling and potential condensation points.

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A Comprehensive Overview of Insulating Wallpaper and Thermal Liner Solutions

Insulating wallpaper, also called thermal liner or insulated wallpaper, presents an innovative approach to enhancing insulation within interiors. This solution offers a convenient application similar to traditional wallpaper, providing a practical and straightforward method of improving insulation. Though not extensively thick, ranging from 3 to 10mm, it offers a moderate level of insulation.

Prominent Product: Sempatap Thermal A notable player in this market is the Sempatap Thermal product line. Distinguished by its 10mm “Magic Wallpaper,” Sempatap Thermal surpasses older polystyrene wall insulation with its Class M1 fire rating. This exceptional construction facilitates redecoration, filling, and even tiling. Impressively, it boasts high insulation ratings in terms of both heat and sound, effectively countering condensation-related issues. Notably, a specialised Sempatap variant is designed for flooring purposes, known as Sempafloor.

Physical Characteristics and Application: Sempatap is supplied in rolls measuring 1m in width and 12.5m in length. Its application mimics wallpaper installation and necessitates the use of dedicated Sempatap adhesive. Seams are seamlessly sealed using decorators’ caulk; post-application, the walls can be decorated in line with the original walls. The wallpaper can be easily removed from Sempatap walls through steam stripping. Minor damage to the fibreglass surface can be rectified using polyfill or plaster. Notably, Sempatap boasts a longevity surpassing plasterboard and can be adhered to ceilings. Beyond its insulation benefits, it significantly reduces noise transmission.

Efficacy and Cost Considerations: Given its modest insulation thickness, this solution isn’t a panacea for substantial heat retention; however, it presents a cost-effective and convenient option. In a Telegraph article, Jeff Howell estimates an approximate cost of £18 per square meter, with a potential payback period of around 60 years due to its limited insulation properties. It’s imperative to ensure proper measures are taken to prevent condensation, including surface dryness and manufacturer-recommended waterproofing barriers.

Additional Benefits: Sempatap originated in France, where it found utility primarily as a soundproofing material, rendering it valuable for noise insulation. Furthermore, insulation wallpapers adeptly conceal cracks that can emerge in structurally mobile homes, owing to their inherent flexibility that accommodates such shifts.

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Common Variants of Insulation Wallpaper and Thermal Liners:

  1. Sempatap: Renowned as a prominent brand in insulation wallpaper solutions.
  2. Wallrock Thermal Liner: A favoured alternative to Sempatap, offering comparable benefits.
  3. Wallrock KV600 Thermal Liner: A slightly thicker variant of the original Wallrock Thermal Liner, yielding enhanced insulation at a higher cost.
  4. Polystyrene Wall Insulation: An economical yet practical choice for insulating wallpaper, though marginally less robust than other offerings.

Installation of Rigid Insulation Boards for Enhanced Wall Insulation

An advanced approach in wall insulation involves the utilisation of rigid insulation boards. These boards can encompass insulated plaster or specialised products incorporating insulation securely bonded onto plasterboard, with a strategically positioned vapour barrier sandwiched between the layers.

Installation Process: Following meticulous wall preparation, the insulated plasterboards can be affixed directly to the surface using adhesives or mechanically fastened with screws. The wall’s condition must be optimal and relatively even. Before installation, a thorough assessment for dampness is essential, as failure to do so may lead to concealed issues over time.

Fixing Method Considerations: While screws facilitate secure attachment, they inadvertently compromise the moisture barrier. Despite this drawback, screws might be necessary for ensuring a steadfast installation. Alternatively, affix battens to the wall before attaching the insulation boards. However, treated battens must be used to counteract the potential cooling effect caused by the added insulation, potentially leading to condensation. The contemplation of damp-proofing courses (DPC) between the batten and the wall can mitigate moisture’s impact on the wooden batten.

Sealing and Gap Management: Interstices between the insulation boards require sealing with mastic to maintain an uninterrupted moisture barrier. While skim plastering is feasible, the cautious approach advises against such risks, given the effort invested in the insulation. Ensuring a continuous vapour barrier at the bottom, where the wall meets the floor, is crucial. Additionally, insulation of floor voids is recommended for comprehensive thermal enhancement.

Advantages and Suitability: This method boasts notable advantages in cost-effectiveness and expeditious implementation. Suited for adept DIY enthusiasts, this technique significantly outperforms thermal liner or insulating wallpaper solutions. Enhanced energy efficiency translates to appreciable reductions in heating expenses, offering a reasonable payback period (typically under 20 years, possibly less), especially when self-installed. Notably, the method’s applicability hinges on the wall’s initial flatness.

Challenges and Object Fixation: Fixing objects onto insulated walls presents challenges, as the insulation material lacks load-bearing capacity. Fixtures must be anchored through to the underlying wall for lasting stability. This complexity arises when attaching weighty items like kitchen cabinets and TV brackets. Strategic placement of battens can circumvent this predicament, necessitating meticulous planning to ensure optimal positioning.

Material Considerations: Materials employed for solid wall insulation entail higher costs than standard insulating wallpaper or conventional insulation. Nonetheless, the practical and straightforward installation process renders this approach a compelling alternative to internal wall insulation.

Enhancing Internal Insulation with Warm Battens

The employment of Warm Battens presents an alternative approach to applying internal wall insulation, closely resembling the method delineated earlier. Noteworthy distinctions lie in the placement of battens atop or within the insulation, serving as a direct anchoring substrate for plasterboards.

While less prevalent due to its intricacy and time-intensive nature, this technique offers discernible merits. Battens, situated away from the frigid wall surface, mitigate susceptibility to decay induced by condensation and moisture. Positioned immediately beneath the plasterboards, they furnish robust anchor points for the secure affixation of substantial objects, such as television sets and kitchen installations.

The strategic incorporation of battens permits the utilisation of more pliable and cost-effective insulation materials, as the battens uphold their structural integrity. This facet can partially offset the supplementary expenditures, both in terms of cost and installation duration, associated with employing battens.

Another prevalent configuration involves integrating the insulation between the battens. Although affording somewhat lesser safeguarding for the wooden battens, this configuration still furnishes a robust foundation for affixing plasterboards and supporting weighty fixtures suspended on the wall.

Prudent consideration must be given to the placement of the vapour barrier. Generally, its placement should minimise perforations incurred from fastenings. Given that battens are affixed to the wall via screws, which entail perforations, the vapour barrier is typically situated atop the battens and positioned at the rear of the plasterboards.

The aluminium foil backing inherent in various insulation boards, such as Celotex and Kingspan, generally fulfils the role of a suitable vapour barrier. A distinct vapour barrier procurement becomes necessary if one opts for expanded polystyrene insulation.

Furthermore, an intervening air gap between the battens, insulation, and the existing wall could be contemplated. This delineates a transition towards the Stud Wall methodology of internal insulation.

Internal Wall Insulation Methods: Stud Wall Construction

The stud wall construction method strategically removes battens from the existing wall to establish a void space behind the newly insulated stud wall. It is recommended that the stud wall is designed to be 100 mm thick, leaving a 50 mm gap for optimal insulation. Detailed instructions on constructing a stud wall can be found here.

While effective, it’s important to note that this approach is characterised by higher costs and more extensive time investment. Additionally, it results in a notable reduction of internal space. Its insulation efficacy is comparable to the method where insulation is directly applied to the wall unless the existing wall is afflicted by dampness. In such cases, proper ventilation of the void space behind the stud wall becomes crucial, allowing moisture from the wall to dissipate.

This overview encompasses the complete spectrum of available options for internal wall insulation. During the self-installation of insulation, a few challenging areas may necessitate thoughtful pre-planning.

Managing Services and Openings with Internal Wall Insulation

When integrating essential services such as wiring and pipe work within an internally insulated wall, the most effective approach involves establishing a designated service void within the wall structure. While this might not be necessary for every scenario, ensuring a robust seal around any instances where pipework or wiring penetrates the vapour barrier is imperative.

The service void’s strategic placement on the vapour barrier’s interior side is crucial. This can be accomplished by introducing an additional layer of battens, creating a space between the insulation material and the plasterboard, and accommodating the passage of services.

Addressing the architectural features around doors and windows, commonly referred to as reveals, presents a challenging aspect of incorporating insulation into interior walls. This task holds paramount importance due to the significant heat loss that can occur in this area and the potential for thermal bridging.

Due to the inherent space limitations within reveals, removing existing plaster from the wall will likely be necessary. Following this, the insulation can be installed and covered with plasterboard. Establishing an effective seal between the insulation and the door or window frame is critical.

Undertaking an internal wall insulation project can be approached as a feasible do-it-yourself endeavour. Considering that a substantial portion of the associated costs is attributed to labour, significant cost savings can be achieved by opting for a self-directed approach.

Furthermore, this undertaking yields substantial returns through energy savings, reducing utility bills. A key piece of advice is to invest in high-quality materials, as the insulating properties of the selected insulation significantly impact the overall efficacy of the project’s outcomes.

Useful links:

How to insulate internal walls

Can internal wall insulation cause damp?

How much does internal wall insulation cost?

What is the best insulation for internal walls?

Does internal wall insulation cause condensation?

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Jake Fitzgerald - Damp Surveyor

Surveyor of Timber & Dampness in Buildings (CSTDB) & ( MRICS ) Chartered Quantity Surveyor

Jake is a qualified chartered quantity surveyor and experienced damp specialist with a unique skill set in thermal imaging. With a focus on effective solutions, Jake combines his expertise in quantity surveying and thermal imaging to accurately assess and address damp-related issues. He utilises advanced technology to identify hidden moisture sources and develop targeted strategies, ensuring comprehensive and cost-effective solutions for his clients. With a commitment to open communication and client satisfaction, Jake delivers cutting-edge solutions that tackle damp challenges head-on.

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