House of Quality (QFD)
Translate what customers want into what engineers build. The House of Quality, the core matrix of Quality Function Deployment, links customer requirements to technical characteristics, weights them, sets targets and benchmarks competitors, so design decisions trace back to the Voice of the Customer.
Build House of Quality →What is the House of Quality?
The House of Quality is the central matrix of Quality Function Deployment (QFD), a method for translating customer requirements into technical design specifications. Named for its house-like shape, complete with a roof, it systematically connects what customers want (the whats) to how the organization will deliver it (the hows).
The structure has several linked parts: customer requirements with importance weights on the left, technical characteristics across the top, a central relationship matrix showing how strongly each technical characteristic affects each customer requirement, a correlation roof showing how the technical characteristics interact with each other, a competitive assessment, and target values for the technical characteristics at the bottom.
Its purpose is deployment: ensuring that the Voice of the Customer drives the technical targets the organization commits to, rather than engineering priorities being set in isolation. By making the links explicit, the House of Quality reveals which technical characteristics matter most for satisfying customers and where technical trade-offs exist.
In plain terms: The House of Quality is a structured matrix that connects customer wants to engineering hows. Customer needs go down the side with importance weights, technical measures go across the top, and the grid shows which measures affect which needs. The 'roof' shows where technical choices conflict. It's how you make sure the design actually serves the customer.
Parts of the House
Whats & Hows
Customer requirements (whats) with importance weights on the left; technical characteristics (hows) across the top.
Relationship Matrix
The central grid rates how strongly each technical characteristic affects each customer requirement, usually strong, medium or weak.
Roof, Benchmark & Targets
The correlation roof shows technical interactions; a competitive assessment compares offerings; target values set the design goals.
Key Formulas
Reading the House
The weighted relationship scores at the bottom rank the technical characteristics by how much they contribute to satisfying weighted customer requirements. These priorities tell engineering where to focus, and they trace directly back to customer importance rather than internal preference.
The correlation roof is where trade-offs surface. A negative correlation between two technical characteristics means improving one worsens the other, a technical contradiction that must be managed, and sometimes a candidate for TRIZ-style resolution rather than compromise.
Assumptions & Validation
Valid Customer Input
Customer requirements and weights come from genuine VOC.
If violated: Gather and prioritize VOC before building the house.
Measurable Technical Characteristics
The hows are measurable characteristics, not solutions.
If violated: Restate any how that is a solution as a measurable characteristic.
Honest Relationships
Relationship and correlation ratings reflect real effects.
If violated: Base ratings on evidence and engineering judgment.
⚠️ Check assumptions first
The House of Quality is powerful but can become an enormous, over-detailed matrix that consumes effort without adding insight. Keep the number of whats and hows manageable, and focus on the strong relationships and the negative correlations in the roof, which are where the real decisions and trade-offs lie. And the whole structure rests on valid, prioritized Voice of the Customer input; without it, the house deploys the wrong requirements precisely.
When NOT to Use House of Quality (QFD)
Gathering Needs
To collect and prioritize customer needs first, use VOC, CTQ trees and Kano analysis.
Simple Relationship Mapping
For a basic relationship grid without the full QFD structure, a matrix diagram suffices.
Concept Selection
To choose among design concepts, use Pugh analysis.
Industry Applications
Requirement Deployment
Translate prioritized customer requirements into weighted technical targets for design.
Design Prioritization
Identify which technical characteristics most affect customer satisfaction.
Trade-off Management
Surface negative technical correlations that must be managed or resolved.
Competitive Design
Benchmark technical performance against competitors to set target values.
Frequently Asked Questions
What is the House of Quality?
The House of Quality is the central matrix of Quality Function Deployment, used to translate customer requirements into technical design specifications. Named for its house-like shape with a correlation roof, it links what customers want to how the organization will deliver it, through a relationship matrix, importance weights, a competitive assessment and target values. Its purpose is to ensure the Voice of the Customer drives the technical decisions of design.
What is Quality Function Deployment (QFD)?
Quality Function Deployment is a structured method for translating customer requirements into technical specifications throughout product or process development. The House of Quality is its first and best-known matrix. QFD systematically deploys the Voice of the Customer, ensuring that customer needs, rather than internal engineering preferences, drive the characteristics and targets the organization commits to at each stage of design.
What is the correlation roof in the House of Quality?
The correlation roof is the triangular top of the House of Quality that shows how the technical characteristics interact with one another. A positive correlation means improving one characteristic helps another, while a negative correlation means improving one worsens another, a technical trade-off. The roof surfaces these interactions so that conflicting requirements can be managed deliberately rather than discovered late in design.
How are technical priorities calculated?
Each technical characteristic's priority is derived by combining the importance weights of the customer requirements with the strength of its relationship to each requirement, then summing across requirements. Technical characteristics that strongly affect highly weighted customer requirements receive the highest priority. This traces engineering focus directly back to what customers value most, rather than to internal assumptions about what matters.
What is the difference between the whats and the hows?
The whats are the customer requirements, what customers want, listed with importance weights on the left of the house. The hows are the technical characteristics, the measurable ways the organization will deliver those requirements, listed across the top. The relationship matrix connects them, showing how strongly each how affects each what. Keeping the hows as measurable characteristics rather than solutions is essential to the method.
How does the House of Quality relate to VOC and CTQ trees?
Voice of Customer work gathers customer needs, and a CTQ tree translates them into measurable requirements. The House of Quality then takes those prioritized requirements as its whats and deploys them into technical characteristics and targets. In this sequence, VOC and CTQ trees supply and structure the customer input, while the House of Quality connects that input to the technical decisions of design, completing the deployment.
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